1 /* 2 * Copyright (c) 1994, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 import java.io.ObjectStreamField; 29 import java.io.UnsupportedEncodingException; 30 import java.nio.charset.Charset; 31 import java.util.ArrayList; 32 import java.util.Arrays; 33 import java.util.Comparator; 34 import java.util.Formatter; 35 import java.util.Locale; 36 import java.util.Objects; 37 import java.util.Spliterator; 38 import java.util.StringJoiner; 39 import java.util.function.IntConsumer; 40 import java.util.regex.Matcher; 41 import java.util.regex.Pattern; 42 import java.util.regex.PatternSyntaxException; 43 import java.util.stream.IntStream; 44 import java.util.stream.StreamSupport; 45 import jdk.internal.HotSpotIntrinsicCandidate; 46 47 /** 48 * The {@code String} class represents character strings. All 49 * string literals in Java programs, such as {@code "abc"}, are 50 * implemented as instances of this class. 51 * <p> 52 * Strings are constant; their values cannot be changed after they 53 * are created. String buffers support mutable strings. 54 * Because String objects are immutable they can be shared. For example: 55 * <blockquote><pre> 56 * String str = "abc"; 57 * </pre></blockquote><p> 58 * is equivalent to: 59 * <blockquote><pre> 60 * char data[] = {'a', 'b', 'c'}; 61 * String str = new String(data); 62 * </pre></blockquote><p> 63 * Here are some more examples of how strings can be used: 64 * <blockquote><pre> 65 * System.out.println("abc"); 66 * String cde = "cde"; 67 * System.out.println("abc" + cde); 68 * String c = "abc".substring(2,3); 69 * String d = cde.substring(1, 2); 70 * </pre></blockquote> 71 * <p> 72 * The class {@code String} includes methods for examining 73 * individual characters of the sequence, for comparing strings, for 74 * searching strings, for extracting substrings, and for creating a 75 * copy of a string with all characters translated to uppercase or to 76 * lowercase. Case mapping is based on the Unicode Standard version 77 * specified by the {@link java.lang.Character Character} class. 78 * <p> 79 * The Java language provides special support for the string 80 * concatenation operator ( + ), and for conversion of 81 * other objects to strings. String concatenation is implemented 82 * through the {@code StringBuilder}(or {@code StringBuffer}) 83 * class and its {@code append} method. 84 * String conversions are implemented through the method 85 * {@code toString}, defined by {@code Object} and 86 * inherited by all classes in Java. For additional information on 87 * string concatenation and conversion, see Gosling, Joy, and Steele, 88 * <i>The Java Language Specification</i>. 89 * 90 * <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor 91 * or method in this class will cause a {@link NullPointerException} to be 92 * thrown. 93 * 94 * <p>A {@code String} represents a string in the UTF-16 format 95 * in which <em>supplementary characters</em> are represented by <em>surrogate 96 * pairs</em> (see the section <a href="Character.html#unicode">Unicode 97 * Character Representations</a> in the {@code Character} class for 98 * more information). 99 * Index values refer to {@code char} code units, so a supplementary 100 * character uses two positions in a {@code String}. 101 * <p>The {@code String} class provides methods for dealing with 102 * Unicode code points (i.e., characters), in addition to those for 103 * dealing with Unicode code units (i.e., {@code char} values). 104 * 105 * @author Lee Boynton 106 * @author Arthur van Hoff 107 * @author Martin Buchholz 108 * @author Ulf Zibis 109 * @see java.lang.Object#toString() 110 * @see java.lang.StringBuffer 111 * @see java.lang.StringBuilder 112 * @see java.nio.charset.Charset 113 * @since 1.0 114 */ 115 116 public final class String 117 implements java.io.Serializable, Comparable<String>, CharSequence { 118 /** The value is used for character storage. */ 119 private final char value[]; 120 121 /** Cache the hash code for the string */ 122 private int hash; // Default to 0 123 124 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 125 private static final long serialVersionUID = -6849794470754667710L; 126 127 /** 128 * Class String is special cased within the Serialization Stream Protocol. 129 * 130 * A String instance is written into an ObjectOutputStream according to 131 * <a href="{@docRoot}/../platform/serialization/spec/output.html"> 132 * Object Serialization Specification, Section 6.2, "Stream Elements"</a> 133 */ 134 private static final ObjectStreamField[] serialPersistentFields = 135 new ObjectStreamField[0]; 136 137 /** 138 * Initializes a newly created {@code String} object so that it represents 139 * an empty character sequence. Note that use of this constructor is 140 * unnecessary since Strings are immutable. 141 */ 142 public String() { 143 this.value = "".value; 144 } 145 146 /** 147 * Initializes a newly created {@code String} object so that it represents 148 * the same sequence of characters as the argument; in other words, the 149 * newly created string is a copy of the argument string. Unless an 150 * explicit copy of {@code original} is needed, use of this constructor is 151 * unnecessary since Strings are immutable. 152 * 153 * @param original 154 * A {@code String} 155 */ 156 @HotSpotIntrinsicCandidate 157 public String(String original) { 158 this.value = original.value; 159 this.hash = original.hash; 160 } 161 162 /** 163 * Allocates a new {@code String} so that it represents the sequence of 164 * characters currently contained in the character array argument. The 165 * contents of the character array are copied; subsequent modification of 166 * the character array does not affect the newly created string. 167 * 168 * @param value 169 * The initial value of the string 170 */ 171 public String(char value[]) { 172 this.value = Arrays.copyOf(value, value.length); 173 } 174 175 /** 176 * Allocates a new {@code String} that contains characters from a subarray 177 * of the character array argument. The {@code offset} argument is the 178 * index of the first character of the subarray and the {@code count} 179 * argument specifies the length of the subarray. The contents of the 180 * subarray are copied; subsequent modification of the character array does 181 * not affect the newly created string. 182 * 183 * @param value 184 * Array that is the source of characters 185 * 186 * @param offset 187 * The initial offset 188 * 189 * @param count 190 * The length 191 * 192 * @throws IndexOutOfBoundsException 193 * If {@code offset} is negative, {@code count} is negative, or 194 * {@code offset} is greater than {@code value.length - count} 195 */ 196 public String(char value[], int offset, int count) { 197 if (offset < 0) { 198 throw new StringIndexOutOfBoundsException(offset); 199 } 200 if (count <= 0) { 201 if (count < 0) { 202 throw new StringIndexOutOfBoundsException(count); 203 } 204 if (offset <= value.length) { 205 this.value = "".value; 206 return; 207 } 208 } 209 // Note: offset or count might be near -1>>>1. 210 if (offset > value.length - count) { 211 throw new StringIndexOutOfBoundsException(offset + count); 212 } 213 this.value = Arrays.copyOfRange(value, offset, offset + count); 214 } 215 216 /** 217 * Allocates a new {@code String} that contains characters from a subarray 218 * of the <a href="Character.html#unicode">Unicode code point</a> array 219 * argument. The {@code offset} argument is the index of the first code 220 * point of the subarray and the {@code count} argument specifies the 221 * length of the subarray. The contents of the subarray are converted to 222 * {@code char}s; subsequent modification of the {@code int} array does not 223 * affect the newly created string. 224 * 225 * @param codePoints 226 * Array that is the source of Unicode code points 227 * 228 * @param offset 229 * The initial offset 230 * 231 * @param count 232 * The length 233 * 234 * @throws IllegalArgumentException 235 * If any invalid Unicode code point is found in {@code 236 * codePoints} 237 * 238 * @throws IndexOutOfBoundsException 239 * If {@code offset} is negative, {@code count} is negative, or 240 * {@code offset} is greater than {@code codePoints.length - count} 241 * 242 * @since 1.5 243 */ 244 public String(int[] codePoints, int offset, int count) { 245 if (offset < 0) { 246 throw new StringIndexOutOfBoundsException(offset); 247 } 248 if (count <= 0) { 249 if (count < 0) { 250 throw new StringIndexOutOfBoundsException(count); 251 } 252 if (offset <= codePoints.length) { 253 this.value = "".value; 254 return; 255 } 256 } 257 // Note: offset or count might be near -1>>>1. 258 if (offset > codePoints.length - count) { 259 throw new StringIndexOutOfBoundsException(offset + count); 260 } 261 262 final int end = offset + count; 263 264 // Pass 1: Compute precise size of char[] 265 int n = count; 266 for (int i = offset; i < end; i++) { 267 int c = codePoints[i]; 268 if (Character.isBmpCodePoint(c)) 269 continue; 270 else if (Character.isValidCodePoint(c)) 271 n++; 272 else throw new IllegalArgumentException(Integer.toString(c)); 273 } 274 275 // Pass 2: Allocate and fill in char[] 276 final char[] v = new char[n]; 277 278 for (int i = offset, j = 0; i < end; i++, j++) { 279 int c = codePoints[i]; 280 if (Character.isBmpCodePoint(c)) 281 v[j] = (char)c; 282 else 283 Character.toSurrogates(c, v, j++); 284 } 285 286 this.value = v; 287 } 288 289 /** 290 * Allocates a new {@code String} constructed from a subarray of an array 291 * of 8-bit integer values. 292 * 293 * <p> The {@code offset} argument is the index of the first byte of the 294 * subarray, and the {@code count} argument specifies the length of the 295 * subarray. 296 * 297 * <p> Each {@code byte} in the subarray is converted to a {@code char} as 298 * specified in the method above. 299 * 300 * @deprecated This method does not properly convert bytes into characters. 301 * As of JDK 1.1, the preferred way to do this is via the 302 * {@code String} constructors that take a {@link 303 * java.nio.charset.Charset}, charset name, or that use the platform's 304 * default charset. 305 * 306 * @param ascii 307 * The bytes to be converted to characters 308 * 309 * @param hibyte 310 * The top 8 bits of each 16-bit Unicode code unit 311 * 312 * @param offset 313 * The initial offset 314 * @param count 315 * The length 316 * 317 * @throws IndexOutOfBoundsException 318 * If {@code offset} is negative, {@code count} is negative, or 319 * {@code offset} is greater than {@code ascii.length - count} 320 * 321 * @see #String(byte[], int) 322 * @see #String(byte[], int, int, java.lang.String) 323 * @see #String(byte[], int, int, java.nio.charset.Charset) 324 * @see #String(byte[], int, int) 325 * @see #String(byte[], java.lang.String) 326 * @see #String(byte[], java.nio.charset.Charset) 327 * @see #String(byte[]) 328 */ 329 @Deprecated 330 public String(byte ascii[], int hibyte, int offset, int count) { 331 checkBounds(ascii, offset, count); 332 char[] value = new char[count]; 333 334 if (hibyte == 0) { 335 for (int i = count; i-- > 0;) { 336 value[i] = (char)(ascii[i + offset] & 0xff); 337 } 338 } else { 339 hibyte <<= 8; 340 for (int i = count; i-- > 0;) { 341 value[i] = (char)(hibyte | (ascii[i + offset] & 0xff)); 342 } 343 } 344 this.value = value; 345 } 346 347 /** 348 * Allocates a new {@code String} containing characters constructed from 349 * an array of 8-bit integer values. Each character <i>c</i>in the 350 * resulting string is constructed from the corresponding component 351 * <i>b</i> in the byte array such that: 352 * 353 * <blockquote><pre> 354 * <b><i>c</i></b> == (char)(((hibyte & 0xff) << 8) 355 * | (<b><i>b</i></b> & 0xff)) 356 * </pre></blockquote> 357 * 358 * @deprecated This method does not properly convert bytes into 359 * characters. As of JDK 1.1, the preferred way to do this is via the 360 * {@code String} constructors that take a {@link 361 * java.nio.charset.Charset}, charset name, or that use the platform's 362 * default charset. 363 * 364 * @param ascii 365 * The bytes to be converted to characters 366 * 367 * @param hibyte 368 * The top 8 bits of each 16-bit Unicode code unit 369 * 370 * @see #String(byte[], int, int, java.lang.String) 371 * @see #String(byte[], int, int, java.nio.charset.Charset) 372 * @see #String(byte[], int, int) 373 * @see #String(byte[], java.lang.String) 374 * @see #String(byte[], java.nio.charset.Charset) 375 * @see #String(byte[]) 376 */ 377 @Deprecated 378 public String(byte ascii[], int hibyte) { 379 this(ascii, hibyte, 0, ascii.length); 380 } 381 382 /* Common private utility method used to bounds check the byte array 383 * and requested offset & length values used by the String(byte[],..) 384 * constructors. 385 */ 386 private static void checkBounds(byte[] bytes, int offset, int length) { 387 if (length < 0) 388 throw new StringIndexOutOfBoundsException(length); 389 if (offset < 0) 390 throw new StringIndexOutOfBoundsException(offset); 391 if (offset > bytes.length - length) 392 throw new StringIndexOutOfBoundsException(offset + length); 393 } 394 395 /** 396 * Constructs a new {@code String} by decoding the specified subarray of 397 * bytes using the specified charset. The length of the new {@code String} 398 * is a function of the charset, and hence may not be equal to the length 399 * of the subarray. 400 * 401 * <p> The behavior of this constructor when the given bytes are not valid 402 * in the given charset is unspecified. The {@link 403 * java.nio.charset.CharsetDecoder} class should be used when more control 404 * over the decoding process is required. 405 * 406 * @param bytes 407 * The bytes to be decoded into characters 408 * 409 * @param offset 410 * The index of the first byte to decode 411 * 412 * @param length 413 * The number of bytes to decode 414 415 * @param charsetName 416 * The name of a supported {@linkplain java.nio.charset.Charset 417 * charset} 418 * 419 * @throws UnsupportedEncodingException 420 * If the named charset is not supported 421 * 422 * @throws IndexOutOfBoundsException 423 * If {@code offset} is negative, {@code length} is negative, or 424 * {@code offset} is greater than {@code bytes.length - length} 425 * 426 * @since 1.1 427 */ 428 public String(byte bytes[], int offset, int length, String charsetName) 429 throws UnsupportedEncodingException { 430 if (charsetName == null) 431 throw new NullPointerException("charsetName"); 432 checkBounds(bytes, offset, length); 433 this.value = StringCoding.decode(charsetName, bytes, offset, length); 434 } 435 436 /** 437 * Constructs a new {@code String} by decoding the specified subarray of 438 * bytes using the specified {@linkplain java.nio.charset.Charset charset}. 439 * The length of the new {@code String} is a function of the charset, and 440 * hence may not be equal to the length of the subarray. 441 * 442 * <p> This method always replaces malformed-input and unmappable-character 443 * sequences with this charset's default replacement string. The {@link 444 * java.nio.charset.CharsetDecoder} class should be used when more control 445 * over the decoding process is required. 446 * 447 * @param bytes 448 * The bytes to be decoded into characters 449 * 450 * @param offset 451 * The index of the first byte to decode 452 * 453 * @param length 454 * The number of bytes to decode 455 * 456 * @param charset 457 * The {@linkplain java.nio.charset.Charset charset} to be used to 458 * decode the {@code bytes} 459 * 460 * @throws IndexOutOfBoundsException 461 * If {@code offset} is negative, {@code length} is negative, or 462 * {@code offset} is greater than {@code bytes.length - length} 463 * 464 * @since 1.6 465 */ 466 public String(byte bytes[], int offset, int length, Charset charset) { 467 if (charset == null) 468 throw new NullPointerException("charset"); 469 checkBounds(bytes, offset, length); 470 this.value = StringCoding.decode(charset, bytes, offset, length); 471 } 472 473 /** 474 * Constructs a new {@code String} by decoding the specified array of bytes 475 * using the specified {@linkplain java.nio.charset.Charset charset}. The 476 * length of the new {@code String} is a function of the charset, and hence 477 * may not be equal to the length of the byte array. 478 * 479 * <p> The behavior of this constructor when the given bytes are not valid 480 * in the given charset is unspecified. The {@link 481 * java.nio.charset.CharsetDecoder} class should be used when more control 482 * over the decoding process is required. 483 * 484 * @param bytes 485 * The bytes to be decoded into characters 486 * 487 * @param charsetName 488 * The name of a supported {@linkplain java.nio.charset.Charset 489 * charset} 490 * 491 * @throws UnsupportedEncodingException 492 * If the named charset is not supported 493 * 494 * @since 1.1 495 */ 496 public String(byte bytes[], String charsetName) 497 throws UnsupportedEncodingException { 498 this(bytes, 0, bytes.length, charsetName); 499 } 500 501 /** 502 * Constructs a new {@code String} by decoding the specified array of 503 * bytes using the specified {@linkplain java.nio.charset.Charset charset}. 504 * The length of the new {@code String} is a function of the charset, and 505 * hence may not be equal to the length of the byte array. 506 * 507 * <p> This method always replaces malformed-input and unmappable-character 508 * sequences with this charset's default replacement string. The {@link 509 * java.nio.charset.CharsetDecoder} class should be used when more control 510 * over the decoding process is required. 511 * 512 * @param bytes 513 * The bytes to be decoded into characters 514 * 515 * @param charset 516 * The {@linkplain java.nio.charset.Charset charset} to be used to 517 * decode the {@code bytes} 518 * 519 * @since 1.6 520 */ 521 public String(byte bytes[], Charset charset) { 522 this(bytes, 0, bytes.length, charset); 523 } 524 525 /** 526 * Constructs a new {@code String} by decoding the specified subarray of 527 * bytes using the platform's default charset. The length of the new 528 * {@code String} is a function of the charset, and hence may not be equal 529 * to the length of the subarray. 530 * 531 * <p> The behavior of this constructor when the given bytes are not valid 532 * in the default charset is unspecified. The {@link 533 * java.nio.charset.CharsetDecoder} class should be used when more control 534 * over the decoding process is required. 535 * 536 * @param bytes 537 * The bytes to be decoded into characters 538 * 539 * @param offset 540 * The index of the first byte to decode 541 * 542 * @param length 543 * The number of bytes to decode 544 * 545 * @throws IndexOutOfBoundsException 546 * If {@code offset} is negative, {@code length} is negative, or 547 * {@code offset} is greater than {@code bytes.length - length} 548 * 549 * @since 1.1 550 */ 551 public String(byte bytes[], int offset, int length) { 552 checkBounds(bytes, offset, length); 553 this.value = StringCoding.decode(bytes, offset, length); 554 } 555 556 /** 557 * Constructs a new {@code String} by decoding the specified array of bytes 558 * using the platform's default charset. The length of the new {@code 559 * String} is a function of the charset, and hence may not be equal to the 560 * length of the byte array. 561 * 562 * <p> The behavior of this constructor when the given bytes are not valid 563 * in the default charset is unspecified. The {@link 564 * java.nio.charset.CharsetDecoder} class should be used when more control 565 * over the decoding process is required. 566 * 567 * @param bytes 568 * The bytes to be decoded into characters 569 * 570 * @since 1.1 571 */ 572 public String(byte[] bytes) { 573 this(bytes, 0, bytes.length); 574 } 575 576 /** 577 * Allocates a new string that contains the sequence of characters 578 * currently contained in the string buffer argument. The contents of the 579 * string buffer are copied; subsequent modification of the string buffer 580 * does not affect the newly created string. 581 * 582 * @param buffer 583 * A {@code StringBuffer} 584 */ 585 public String(StringBuffer buffer) { 586 synchronized(buffer) { 587 this.value = Arrays.copyOf(buffer.getValue(), buffer.length()); 588 } 589 } 590 591 /** 592 * Allocates a new string that contains the sequence of characters 593 * currently contained in the string builder argument. The contents of the 594 * string builder are copied; subsequent modification of the string builder 595 * does not affect the newly created string. 596 * 597 * <p> This constructor is provided to ease migration to {@code 598 * StringBuilder}. Obtaining a string from a string builder via the {@code 599 * toString} method is likely to run faster and is generally preferred. 600 * 601 * @param builder 602 * A {@code StringBuilder} 603 * 604 * @since 1.5 605 */ 606 public String(StringBuilder builder) { 607 this.value = Arrays.copyOf(builder.getValue(), builder.length()); 608 } 609 610 /* 611 * Package private constructor which shares value array for speed. 612 * this constructor is always expected to be called with share==true. 613 * a separate constructor is needed because we already have a public 614 * String(char[]) constructor that makes a copy of the given char[]. 615 */ 616 String(char[] value, boolean share) { 617 // assert share : "unshared not supported"; 618 this.value = value; 619 } 620 621 /** 622 * Returns the length of this string. 623 * The length is equal to the number of <a href="Character.html#unicode">Unicode 624 * code units</a> in the string. 625 * 626 * @return the length of the sequence of characters represented by this 627 * object. 628 */ 629 public int length() { 630 return value.length; 631 } 632 633 /** 634 * Returns {@code true} if, and only if, {@link #length()} is {@code 0}. 635 * 636 * @return {@code true} if {@link #length()} is {@code 0}, otherwise 637 * {@code false} 638 * 639 * @since 1.6 640 */ 641 public boolean isEmpty() { 642 return value.length == 0; 643 } 644 645 /** 646 * Returns the {@code char} value at the 647 * specified index. An index ranges from {@code 0} to 648 * {@code length() - 1}. The first {@code char} value of the sequence 649 * is at index {@code 0}, the next at index {@code 1}, 650 * and so on, as for array indexing. 651 * 652 * <p>If the {@code char} value specified by the index is a 653 * <a href="Character.html#unicode">surrogate</a>, the surrogate 654 * value is returned. 655 * 656 * @param index the index of the {@code char} value. 657 * @return the {@code char} value at the specified index of this string. 658 * The first {@code char} value is at index {@code 0}. 659 * @exception IndexOutOfBoundsException if the {@code index} 660 * argument is negative or not less than the length of this 661 * string. 662 */ 663 public char charAt(int index) { 664 if ((index < 0) || (index >= value.length)) { 665 throw new StringIndexOutOfBoundsException(index); 666 } 667 return value[index]; 668 } 669 670 /** 671 * Returns the character (Unicode code point) at the specified 672 * index. The index refers to {@code char} values 673 * (Unicode code units) and ranges from {@code 0} to 674 * {@link #length()}{@code - 1}. 675 * 676 * <p> If the {@code char} value specified at the given index 677 * is in the high-surrogate range, the following index is less 678 * than the length of this {@code String}, and the 679 * {@code char} value at the following index is in the 680 * low-surrogate range, then the supplementary code point 681 * corresponding to this surrogate pair is returned. Otherwise, 682 * the {@code char} value at the given index is returned. 683 * 684 * @param index the index to the {@code char} values 685 * @return the code point value of the character at the 686 * {@code index} 687 * @exception IndexOutOfBoundsException if the {@code index} 688 * argument is negative or not less than the length of this 689 * string. 690 * @since 1.5 691 */ 692 public int codePointAt(int index) { 693 if ((index < 0) || (index >= value.length)) { 694 throw new StringIndexOutOfBoundsException(index); 695 } 696 return Character.codePointAtImpl(value, index, value.length); 697 } 698 699 /** 700 * Returns the character (Unicode code point) before the specified 701 * index. The index refers to {@code char} values 702 * (Unicode code units) and ranges from {@code 1} to {@link 703 * CharSequence#length() length}. 704 * 705 * <p> If the {@code char} value at {@code (index - 1)} 706 * is in the low-surrogate range, {@code (index - 2)} is not 707 * negative, and the {@code char} value at {@code (index - 708 * 2)} is in the high-surrogate range, then the 709 * supplementary code point value of the surrogate pair is 710 * returned. If the {@code char} value at {@code index - 711 * 1} is an unpaired low-surrogate or a high-surrogate, the 712 * surrogate value is returned. 713 * 714 * @param index the index following the code point that should be returned 715 * @return the Unicode code point value before the given index. 716 * @exception IndexOutOfBoundsException if the {@code index} 717 * argument is less than 1 or greater than the length 718 * of this string. 719 * @since 1.5 720 */ 721 public int codePointBefore(int index) { 722 int i = index - 1; 723 if ((i < 0) || (i >= value.length)) { 724 throw new StringIndexOutOfBoundsException(index); 725 } 726 return Character.codePointBeforeImpl(value, index, 0); 727 } 728 729 /** 730 * Returns the number of Unicode code points in the specified text 731 * range of this {@code String}. The text range begins at the 732 * specified {@code beginIndex} and extends to the 733 * {@code char} at index {@code endIndex - 1}. Thus the 734 * length (in {@code char}s) of the text range is 735 * {@code endIndex-beginIndex}. Unpaired surrogates within 736 * the text range count as one code point each. 737 * 738 * @param beginIndex the index to the first {@code char} of 739 * the text range. 740 * @param endIndex the index after the last {@code char} of 741 * the text range. 742 * @return the number of Unicode code points in the specified text 743 * range 744 * @exception IndexOutOfBoundsException if the 745 * {@code beginIndex} is negative, or {@code endIndex} 746 * is larger than the length of this {@code String}, or 747 * {@code beginIndex} is larger than {@code endIndex}. 748 * @since 1.5 749 */ 750 public int codePointCount(int beginIndex, int endIndex) { 751 if (beginIndex < 0 || endIndex > value.length || beginIndex > endIndex) { 752 throw new IndexOutOfBoundsException(); 753 } 754 return Character.codePointCountImpl(value, beginIndex, endIndex - beginIndex); 755 } 756 757 /** 758 * Returns the index within this {@code String} that is 759 * offset from the given {@code index} by 760 * {@code codePointOffset} code points. Unpaired surrogates 761 * within the text range given by {@code index} and 762 * {@code codePointOffset} count as one code point each. 763 * 764 * @param index the index to be offset 765 * @param codePointOffset the offset in code points 766 * @return the index within this {@code String} 767 * @exception IndexOutOfBoundsException if {@code index} 768 * is negative or larger then the length of this 769 * {@code String}, or if {@code codePointOffset} is positive 770 * and the substring starting with {@code index} has fewer 771 * than {@code codePointOffset} code points, 772 * or if {@code codePointOffset} is negative and the substring 773 * before {@code index} has fewer than the absolute value 774 * of {@code codePointOffset} code points. 775 * @since 1.5 776 */ 777 public int offsetByCodePoints(int index, int codePointOffset) { 778 if (index < 0 || index > value.length) { 779 throw new IndexOutOfBoundsException(); 780 } 781 return Character.offsetByCodePointsImpl(value, 0, value.length, 782 index, codePointOffset); 783 } 784 785 /** 786 * Copy characters from this string into dst starting at dstBegin. 787 * This method doesn't perform any range checking. 788 */ 789 void getChars(char dst[], int dstBegin) { 790 System.arraycopy(value, 0, dst, dstBegin, value.length); 791 } 792 793 /** 794 * Copies characters from this string into the destination character 795 * array. 796 * <p> 797 * The first character to be copied is at index {@code srcBegin}; 798 * the last character to be copied is at index {@code srcEnd-1} 799 * (thus the total number of characters to be copied is 800 * {@code srcEnd-srcBegin}). The characters are copied into the 801 * subarray of {@code dst} starting at index {@code dstBegin} 802 * and ending at index: 803 * <blockquote><pre> 804 * dstBegin + (srcEnd-srcBegin) - 1 805 * </pre></blockquote> 806 * 807 * @param srcBegin index of the first character in the string 808 * to copy. 809 * @param srcEnd index after the last character in the string 810 * to copy. 811 * @param dst the destination array. 812 * @param dstBegin the start offset in the destination array. 813 * @exception IndexOutOfBoundsException If any of the following 814 * is true: 815 * <ul><li>{@code srcBegin} is negative. 816 * <li>{@code srcBegin} is greater than {@code srcEnd} 817 * <li>{@code srcEnd} is greater than the length of this 818 * string 819 * <li>{@code dstBegin} is negative 820 * <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than 821 * {@code dst.length}</ul> 822 */ 823 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) { 824 if (srcBegin < 0) { 825 throw new StringIndexOutOfBoundsException(srcBegin); 826 } 827 if (srcEnd > value.length) { 828 throw new StringIndexOutOfBoundsException(srcEnd); 829 } 830 if (srcBegin > srcEnd) { 831 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); 832 } 833 System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin); 834 } 835 836 /** 837 * Copies characters from this string into the destination byte array. Each 838 * byte receives the 8 low-order bits of the corresponding character. The 839 * eight high-order bits of each character are not copied and do not 840 * participate in the transfer in any way. 841 * 842 * <p> The first character to be copied is at index {@code srcBegin}; the 843 * last character to be copied is at index {@code srcEnd-1}. The total 844 * number of characters to be copied is {@code srcEnd-srcBegin}. The 845 * characters, converted to bytes, are copied into the subarray of {@code 846 * dst} starting at index {@code dstBegin} and ending at index: 847 * 848 * <blockquote><pre> 849 * dstBegin + (srcEnd-srcBegin) - 1 850 * </pre></blockquote> 851 * 852 * @deprecated This method does not properly convert characters into 853 * bytes. As of JDK 1.1, the preferred way to do this is via the 854 * {@link #getBytes()} method, which uses the platform's default charset. 855 * 856 * @param srcBegin 857 * Index of the first character in the string to copy 858 * 859 * @param srcEnd 860 * Index after the last character in the string to copy 861 * 862 * @param dst 863 * The destination array 864 * 865 * @param dstBegin 866 * The start offset in the destination array 867 * 868 * @throws IndexOutOfBoundsException 869 * If any of the following is true: 870 * <ul> 871 * <li> {@code srcBegin} is negative 872 * <li> {@code srcBegin} is greater than {@code srcEnd} 873 * <li> {@code srcEnd} is greater than the length of this String 874 * <li> {@code dstBegin} is negative 875 * <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code 876 * dst.length} 877 * </ul> 878 */ 879 @Deprecated 880 public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) { 881 if (srcBegin < 0) { 882 throw new StringIndexOutOfBoundsException(srcBegin); 883 } 884 if (srcEnd > value.length) { 885 throw new StringIndexOutOfBoundsException(srcEnd); 886 } 887 if (srcBegin > srcEnd) { 888 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); 889 } 890 Objects.requireNonNull(dst); 891 892 int j = dstBegin; 893 int n = srcEnd; 894 int i = srcBegin; 895 char[] val = value; /* avoid getfield opcode */ 896 897 while (i < n) { 898 dst[j++] = (byte)val[i++]; 899 } 900 } 901 902 /** 903 * Encodes this {@code String} into a sequence of bytes using the named 904 * charset, storing the result into a new byte array. 905 * 906 * <p> The behavior of this method when this string cannot be encoded in 907 * the given charset is unspecified. The {@link 908 * java.nio.charset.CharsetEncoder} class should be used when more control 909 * over the encoding process is required. 910 * 911 * @param charsetName 912 * The name of a supported {@linkplain java.nio.charset.Charset 913 * charset} 914 * 915 * @return The resultant byte array 916 * 917 * @throws UnsupportedEncodingException 918 * If the named charset is not supported 919 * 920 * @since 1.1 921 */ 922 public byte[] getBytes(String charsetName) 923 throws UnsupportedEncodingException { 924 if (charsetName == null) throw new NullPointerException(); 925 return StringCoding.encode(charsetName, value, 0, value.length); 926 } 927 928 /** 929 * Encodes this {@code String} into a sequence of bytes using the given 930 * {@linkplain java.nio.charset.Charset charset}, storing the result into a 931 * new byte array. 932 * 933 * <p> This method always replaces malformed-input and unmappable-character 934 * sequences with this charset's default replacement byte array. The 935 * {@link java.nio.charset.CharsetEncoder} class should be used when more 936 * control over the encoding process is required. 937 * 938 * @param charset 939 * The {@linkplain java.nio.charset.Charset} to be used to encode 940 * the {@code String} 941 * 942 * @return The resultant byte array 943 * 944 * @since 1.6 945 */ 946 public byte[] getBytes(Charset charset) { 947 if (charset == null) throw new NullPointerException(); 948 return StringCoding.encode(charset, value, 0, value.length); 949 } 950 951 /** 952 * Encodes this {@code String} into a sequence of bytes using the 953 * platform's default charset, storing the result into a new byte array. 954 * 955 * <p> The behavior of this method when this string cannot be encoded in 956 * the default charset is unspecified. The {@link 957 * java.nio.charset.CharsetEncoder} class should be used when more control 958 * over the encoding process is required. 959 * 960 * @return The resultant byte array 961 * 962 * @since 1.1 963 */ 964 public byte[] getBytes() { 965 return StringCoding.encode(value, 0, value.length); 966 } 967 968 /** 969 * Compares this string to the specified object. The result is {@code 970 * true} if and only if the argument is not {@code null} and is a {@code 971 * String} object that represents the same sequence of characters as this 972 * object. 973 * 974 * @param anObject 975 * The object to compare this {@code String} against 976 * 977 * @return {@code true} if the given object represents a {@code String} 978 * equivalent to this string, {@code false} otherwise 979 * 980 * @see #compareTo(String) 981 * @see #equalsIgnoreCase(String) 982 */ 983 @HotSpotIntrinsicCandidate 984 public boolean equals(Object anObject) { 985 if (this == anObject) { 986 return true; 987 } 988 if (anObject instanceof String) { 989 char[] v1 = value; 990 char[] v2 = ((String)anObject).value; 991 int n = v1.length; 992 if (n == v2.length) { 993 int i = 0; 994 while (n-- != 0) { 995 if (v1[i] != v2[i]) 996 return false; 997 i++; 998 } 999 return true; 1000 } 1001 } 1002 return false; 1003 } 1004 1005 /** 1006 * Compares this string to the specified {@code StringBuffer}. The result 1007 * is {@code true} if and only if this {@code String} represents the same 1008 * sequence of characters as the specified {@code StringBuffer}. This method 1009 * synchronizes on the {@code StringBuffer}. 1010 * 1011 * @param sb 1012 * The {@code StringBuffer} to compare this {@code String} against 1013 * 1014 * @return {@code true} if this {@code String} represents the same 1015 * sequence of characters as the specified {@code StringBuffer}, 1016 * {@code false} otherwise 1017 * 1018 * @since 1.4 1019 */ 1020 public boolean contentEquals(StringBuffer sb) { 1021 return contentEquals((CharSequence)sb); 1022 } 1023 1024 private boolean nonSyncContentEquals(AbstractStringBuilder sb) { 1025 char[] v1 = value; 1026 char[] v2 = sb.getValue(); 1027 int n = v1.length; 1028 if (n != sb.length()) { 1029 return false; 1030 } 1031 for (int i = 0; i < n; i++) { 1032 if (v1[i] != v2[i]) { 1033 return false; 1034 } 1035 } 1036 return true; 1037 } 1038 1039 /** 1040 * Compares this string to the specified {@code CharSequence}. The 1041 * result is {@code true} if and only if this {@code String} represents the 1042 * same sequence of char values as the specified sequence. Note that if the 1043 * {@code CharSequence} is a {@code StringBuffer} then the method 1044 * synchronizes on it. 1045 * 1046 * @param cs 1047 * The sequence to compare this {@code String} against 1048 * 1049 * @return {@code true} if this {@code String} represents the same 1050 * sequence of char values as the specified sequence, {@code 1051 * false} otherwise 1052 * 1053 * @since 1.5 1054 */ 1055 public boolean contentEquals(CharSequence cs) { 1056 // Argument is a StringBuffer, StringBuilder 1057 if (cs instanceof AbstractStringBuilder) { 1058 if (cs instanceof StringBuffer) { 1059 synchronized(cs) { 1060 return nonSyncContentEquals((AbstractStringBuilder)cs); 1061 } 1062 } else { 1063 return nonSyncContentEquals((AbstractStringBuilder)cs); 1064 } 1065 } 1066 // Argument is a String 1067 if (cs instanceof String) { 1068 return equals(cs); 1069 } 1070 // Argument is a generic CharSequence 1071 char[] v1 = value; 1072 int n = v1.length; 1073 if (n != cs.length()) { 1074 return false; 1075 } 1076 for (int i = 0; i < n; i++) { 1077 if (v1[i] != cs.charAt(i)) { 1078 return false; 1079 } 1080 } 1081 return true; 1082 } 1083 1084 /** 1085 * Compares this {@code String} to another {@code String}, ignoring case 1086 * considerations. Two strings are considered equal ignoring case if they 1087 * are of the same length and corresponding characters in the two strings 1088 * are equal ignoring case. 1089 * 1090 * <p> Two characters {@code c1} and {@code c2} are considered the same 1091 * ignoring case if at least one of the following is true: 1092 * <ul> 1093 * <li> The two characters are the same (as compared by the 1094 * {@code ==} operator) 1095 * <li> Applying the method {@link 1096 * java.lang.Character#toUpperCase(char)} to each character 1097 * produces the same result 1098 * <li> Applying the method {@link 1099 * java.lang.Character#toLowerCase(char)} to each character 1100 * produces the same result 1101 * </ul> 1102 * 1103 * @param anotherString 1104 * The {@code String} to compare this {@code String} against 1105 * 1106 * @return {@code true} if the argument is not {@code null} and it 1107 * represents an equivalent {@code String} ignoring case; {@code 1108 * false} otherwise 1109 * 1110 * @see #equals(Object) 1111 */ 1112 public boolean equalsIgnoreCase(String anotherString) { 1113 return (this == anotherString) ? true 1114 : (anotherString != null) 1115 && (anotherString.value.length == value.length) 1116 && regionMatches(true, 0, anotherString, 0, value.length); 1117 } 1118 1119 /** 1120 * Compares two strings lexicographically. 1121 * The comparison is based on the Unicode value of each character in 1122 * the strings. The character sequence represented by this 1123 * {@code String} object is compared lexicographically to the 1124 * character sequence represented by the argument string. The result is 1125 * a negative integer if this {@code String} object 1126 * lexicographically precedes the argument string. The result is a 1127 * positive integer if this {@code String} object lexicographically 1128 * follows the argument string. The result is zero if the strings 1129 * are equal; {@code compareTo} returns {@code 0} exactly when 1130 * the {@link #equals(Object)} method would return {@code true}. 1131 * <p> 1132 * This is the definition of lexicographic ordering. If two strings are 1133 * different, then either they have different characters at some index 1134 * that is a valid index for both strings, or their lengths are different, 1135 * or both. If they have different characters at one or more index 1136 * positions, let <i>k</i> be the smallest such index; then the string 1137 * whose character at position <i>k</i> has the smaller value, as 1138 * determined by using the < operator, lexicographically precedes the 1139 * other string. In this case, {@code compareTo} returns the 1140 * difference of the two character values at position {@code k} in 1141 * the two string -- that is, the value: 1142 * <blockquote><pre> 1143 * this.charAt(k)-anotherString.charAt(k) 1144 * </pre></blockquote> 1145 * If there is no index position at which they differ, then the shorter 1146 * string lexicographically precedes the longer string. In this case, 1147 * {@code compareTo} returns the difference of the lengths of the 1148 * strings -- that is, the value: 1149 * <blockquote><pre> 1150 * this.length()-anotherString.length() 1151 * </pre></blockquote> 1152 * 1153 * @param anotherString the {@code String} to be compared. 1154 * @return the value {@code 0} if the argument string is equal to 1155 * this string; a value less than {@code 0} if this string 1156 * is lexicographically less than the string argument; and a 1157 * value greater than {@code 0} if this string is 1158 * lexicographically greater than the string argument. 1159 */ 1160 @HotSpotIntrinsicCandidate 1161 public int compareTo(String anotherString) { 1162 char[] v1 = value; 1163 char[] v2 = anotherString.value; 1164 int len1 = v1.length; 1165 int len2 = v2.length; 1166 int lim = Math.min(len1, len2); 1167 1168 for (int k = 0; k < lim; k++) { 1169 char c1 = v1[k]; 1170 char c2 = v2[k]; 1171 if (c1 != c2) { 1172 return c1 - c2; 1173 } 1174 } 1175 return len1 - len2; 1176 } 1177 1178 /** 1179 * A Comparator that orders {@code String} objects as by 1180 * {@code compareToIgnoreCase}. This comparator is serializable. 1181 * <p> 1182 * Note that this Comparator does <em>not</em> take locale into account, 1183 * and will result in an unsatisfactory ordering for certain locales. 1184 * The java.text package provides <em>Collators</em> to allow 1185 * locale-sensitive ordering. 1186 * 1187 * @see java.text.Collator#compare(String, String) 1188 * @since 1.2 1189 */ 1190 public static final Comparator<String> CASE_INSENSITIVE_ORDER 1191 = new CaseInsensitiveComparator(); 1192 private static class CaseInsensitiveComparator 1193 implements Comparator<String>, java.io.Serializable { 1194 // use serialVersionUID from JDK 1.2.2 for interoperability 1195 private static final long serialVersionUID = 8575799808933029326L; 1196 1197 public int compare(String s1, String s2) { 1198 int n1 = s1.length(); 1199 int n2 = s2.length(); 1200 int min = Math.min(n1, n2); 1201 for (int i = 0; i < min; i++) { 1202 char c1 = s1.charAt(i); 1203 char c2 = s2.charAt(i); 1204 if (c1 != c2) { 1205 c1 = Character.toUpperCase(c1); 1206 c2 = Character.toUpperCase(c2); 1207 if (c1 != c2) { 1208 c1 = Character.toLowerCase(c1); 1209 c2 = Character.toLowerCase(c2); 1210 if (c1 != c2) { 1211 // No overflow because of numeric promotion 1212 return c1 - c2; 1213 } 1214 } 1215 } 1216 } 1217 return n1 - n2; 1218 } 1219 1220 /** Replaces the de-serialized object. */ 1221 private Object readResolve() { return CASE_INSENSITIVE_ORDER; } 1222 } 1223 1224 /** 1225 * Compares two strings lexicographically, ignoring case 1226 * differences. This method returns an integer whose sign is that of 1227 * calling {@code compareTo} with normalized versions of the strings 1228 * where case differences have been eliminated by calling 1229 * {@code Character.toLowerCase(Character.toUpperCase(character))} on 1230 * each character. 1231 * <p> 1232 * Note that this method does <em>not</em> take locale into account, 1233 * and will result in an unsatisfactory ordering for certain locales. 1234 * The java.text package provides <em>collators</em> to allow 1235 * locale-sensitive ordering. 1236 * 1237 * @param str the {@code String} to be compared. 1238 * @return a negative integer, zero, or a positive integer as the 1239 * specified String is greater than, equal to, or less 1240 * than this String, ignoring case considerations. 1241 * @see java.text.Collator#compare(String, String) 1242 * @since 1.2 1243 */ 1244 public int compareToIgnoreCase(String str) { 1245 return CASE_INSENSITIVE_ORDER.compare(this, str); 1246 } 1247 1248 /** 1249 * Tests if two string regions are equal. 1250 * <p> 1251 * A substring of this {@code String} object is compared to a substring 1252 * of the argument other. The result is true if these substrings 1253 * represent identical character sequences. The substring of this 1254 * {@code String} object to be compared begins at index {@code toffset} 1255 * and has length {@code len}. The substring of other to be compared 1256 * begins at index {@code ooffset} and has length {@code len}. The 1257 * result is {@code false} if and only if at least one of the following 1258 * is true: 1259 * <ul><li>{@code toffset} is negative. 1260 * <li>{@code ooffset} is negative. 1261 * <li>{@code toffset+len} is greater than the length of this 1262 * {@code String} object. 1263 * <li>{@code ooffset+len} is greater than the length of the other 1264 * argument. 1265 * <li>There is some nonnegative integer <i>k</i> less than {@code len} 1266 * such that: 1267 * {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + } 1268 * <i>k</i>{@code )} 1269 * </ul> 1270 * 1271 * @param toffset the starting offset of the subregion in this string. 1272 * @param other the string argument. 1273 * @param ooffset the starting offset of the subregion in the string 1274 * argument. 1275 * @param len the number of characters to compare. 1276 * @return {@code true} if the specified subregion of this string 1277 * exactly matches the specified subregion of the string argument; 1278 * {@code false} otherwise. 1279 */ 1280 public boolean regionMatches(int toffset, String other, int ooffset, 1281 int len) { 1282 char[] ta = value; 1283 int to = toffset; 1284 char[] pa = other.value; 1285 int po = ooffset; 1286 // Note: toffset, ooffset, or len might be near -1>>>1. 1287 if ((ooffset < 0) || (toffset < 0) 1288 || (toffset > (long)ta.length - len) 1289 || (ooffset > (long)pa.length - len)) { 1290 return false; 1291 } 1292 while (len-- > 0) { 1293 if (ta[to++] != pa[po++]) { 1294 return false; 1295 } 1296 } 1297 return true; 1298 } 1299 1300 /** 1301 * Tests if two string regions are equal. 1302 * <p> 1303 * A substring of this {@code String} object is compared to a substring 1304 * of the argument {@code other}. The result is {@code true} if these 1305 * substrings represent character sequences that are the same, ignoring 1306 * case if and only if {@code ignoreCase} is true. The substring of 1307 * this {@code String} object to be compared begins at index 1308 * {@code toffset} and has length {@code len}. The substring of 1309 * {@code other} to be compared begins at index {@code ooffset} and 1310 * has length {@code len}. The result is {@code false} if and only if 1311 * at least one of the following is true: 1312 * <ul><li>{@code toffset} is negative. 1313 * <li>{@code ooffset} is negative. 1314 * <li>{@code toffset+len} is greater than the length of this 1315 * {@code String} object. 1316 * <li>{@code ooffset+len} is greater than the length of the other 1317 * argument. 1318 * <li>{@code ignoreCase} is {@code false} and there is some nonnegative 1319 * integer <i>k</i> less than {@code len} such that: 1320 * <blockquote><pre> 1321 * this.charAt(toffset+k) != other.charAt(ooffset+k) 1322 * </pre></blockquote> 1323 * <li>{@code ignoreCase} is {@code true} and there is some nonnegative 1324 * integer <i>k</i> less than {@code len} such that: 1325 * <blockquote><pre> 1326 * Character.toLowerCase(this.charAt(toffset+k)) != 1327 Character.toLowerCase(other.charAt(ooffset+k)) 1328 * </pre></blockquote> 1329 * and: 1330 * <blockquote><pre> 1331 * Character.toUpperCase(this.charAt(toffset+k)) != 1332 * Character.toUpperCase(other.charAt(ooffset+k)) 1333 * </pre></blockquote> 1334 * </ul> 1335 * 1336 * @param ignoreCase if {@code true}, ignore case when comparing 1337 * characters. 1338 * @param toffset the starting offset of the subregion in this 1339 * string. 1340 * @param other the string argument. 1341 * @param ooffset the starting offset of the subregion in the string 1342 * argument. 1343 * @param len the number of characters to compare. 1344 * @return {@code true} if the specified subregion of this string 1345 * matches the specified subregion of the string argument; 1346 * {@code false} otherwise. Whether the matching is exact 1347 * or case insensitive depends on the {@code ignoreCase} 1348 * argument. 1349 */ 1350 public boolean regionMatches(boolean ignoreCase, int toffset, 1351 String other, int ooffset, int len) { 1352 char[] ta = value; 1353 int to = toffset; 1354 char[] pa = other.value; 1355 int po = ooffset; 1356 // Note: toffset, ooffset, or len might be near -1>>>1. 1357 if ((ooffset < 0) || (toffset < 0) 1358 || (toffset > (long)ta.length - len) 1359 || (ooffset > (long)pa.length - len)) { 1360 return false; 1361 } 1362 while (len-- > 0) { 1363 char c1 = ta[to++]; 1364 char c2 = pa[po++]; 1365 if (c1 == c2) { 1366 continue; 1367 } 1368 if (ignoreCase) { 1369 // If characters don't match but case may be ignored, 1370 // try converting both characters to uppercase. 1371 // If the results match, then the comparison scan should 1372 // continue. 1373 char u1 = Character.toUpperCase(c1); 1374 char u2 = Character.toUpperCase(c2); 1375 if (u1 == u2) { 1376 continue; 1377 } 1378 // Unfortunately, conversion to uppercase does not work properly 1379 // for the Georgian alphabet, which has strange rules about case 1380 // conversion. So we need to make one last check before 1381 // exiting. 1382 if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) { 1383 continue; 1384 } 1385 } 1386 return false; 1387 } 1388 return true; 1389 } 1390 1391 /** 1392 * Tests if the substring of this string beginning at the 1393 * specified index starts with the specified prefix. 1394 * 1395 * @param prefix the prefix. 1396 * @param toffset where to begin looking in this string. 1397 * @return {@code true} if the character sequence represented by the 1398 * argument is a prefix of the substring of this object starting 1399 * at index {@code toffset}; {@code false} otherwise. 1400 * The result is {@code false} if {@code toffset} is 1401 * negative or greater than the length of this 1402 * {@code String} object; otherwise the result is the same 1403 * as the result of the expression 1404 * <pre> 1405 * this.substring(toffset).startsWith(prefix) 1406 * </pre> 1407 */ 1408 public boolean startsWith(String prefix, int toffset) { 1409 char[] ta = value; 1410 int to = toffset; 1411 char[] pa = prefix.value; 1412 int po = 0; 1413 int pc = pa.length; 1414 // Note: toffset might be near -1>>>1. 1415 if ((toffset < 0) || (toffset > ta.length - pc)) { 1416 return false; 1417 } 1418 while (--pc >= 0) { 1419 if (ta[to++] != pa[po++]) { 1420 return false; 1421 } 1422 } 1423 return true; 1424 } 1425 1426 /** 1427 * Tests if this string starts with the specified prefix. 1428 * 1429 * @param prefix the prefix. 1430 * @return {@code true} if the character sequence represented by the 1431 * argument is a prefix of the character sequence represented by 1432 * this string; {@code false} otherwise. 1433 * Note also that {@code true} will be returned if the 1434 * argument is an empty string or is equal to this 1435 * {@code String} object as determined by the 1436 * {@link #equals(Object)} method. 1437 * @since 1.0 1438 */ 1439 public boolean startsWith(String prefix) { 1440 return startsWith(prefix, 0); 1441 } 1442 1443 /** 1444 * Tests if this string ends with the specified suffix. 1445 * 1446 * @param suffix the suffix. 1447 * @return {@code true} if the character sequence represented by the 1448 * argument is a suffix of the character sequence represented by 1449 * this object; {@code false} otherwise. Note that the 1450 * result will be {@code true} if the argument is the 1451 * empty string or is equal to this {@code String} object 1452 * as determined by the {@link #equals(Object)} method. 1453 */ 1454 public boolean endsWith(String suffix) { 1455 return startsWith(suffix, value.length - suffix.value.length); 1456 } 1457 1458 /** 1459 * Returns a hash code for this string. The hash code for a 1460 * {@code String} object is computed as 1461 * <blockquote><pre> 1462 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1] 1463 * </pre></blockquote> 1464 * using {@code int} arithmetic, where {@code s[i]} is the 1465 * <i>i</i>th character of the string, {@code n} is the length of 1466 * the string, and {@code ^} indicates exponentiation. 1467 * (The hash value of the empty string is zero.) 1468 * 1469 * @return a hash code value for this object. 1470 */ 1471 public int hashCode() { 1472 int h = hash; 1473 if (h == 0) { 1474 for (char v : value) { 1475 h = 31 * h + v; 1476 } 1477 if (h != 0) { 1478 hash = h; 1479 } 1480 } 1481 return h; 1482 } 1483 1484 /** 1485 * Returns the index within this string of the first occurrence of 1486 * the specified character. If a character with value 1487 * {@code ch} occurs in the character sequence represented by 1488 * this {@code String} object, then the index (in Unicode 1489 * code units) of the first such occurrence is returned. For 1490 * values of {@code ch} in the range from 0 to 0xFFFF 1491 * (inclusive), this is the smallest value <i>k</i> such that: 1492 * <blockquote><pre> 1493 * this.charAt(<i>k</i>) == ch 1494 * </pre></blockquote> 1495 * is true. For other values of {@code ch}, it is the 1496 * smallest value <i>k</i> such that: 1497 * <blockquote><pre> 1498 * this.codePointAt(<i>k</i>) == ch 1499 * </pre></blockquote> 1500 * is true. In either case, if no such character occurs in this 1501 * string, then {@code -1} is returned. 1502 * 1503 * @param ch a character (Unicode code point). 1504 * @return the index of the first occurrence of the character in the 1505 * character sequence represented by this object, or 1506 * {@code -1} if the character does not occur. 1507 */ 1508 public int indexOf(int ch) { 1509 return indexOf(ch, 0); 1510 } 1511 1512 /** 1513 * Returns the index within this string of the first occurrence of the 1514 * specified character, starting the search at the specified index. 1515 * <p> 1516 * If a character with value {@code ch} occurs in the 1517 * character sequence represented by this {@code String} 1518 * object at an index no smaller than {@code fromIndex}, then 1519 * the index of the first such occurrence is returned. For values 1520 * of {@code ch} in the range from 0 to 0xFFFF (inclusive), 1521 * this is the smallest value <i>k</i> such that: 1522 * <blockquote><pre> 1523 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex) 1524 * </pre></blockquote> 1525 * is true. For other values of {@code ch}, it is the 1526 * smallest value <i>k</i> such that: 1527 * <blockquote><pre> 1528 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex) 1529 * </pre></blockquote> 1530 * is true. In either case, if no such character occurs in this 1531 * string at or after position {@code fromIndex}, then 1532 * {@code -1} is returned. 1533 * 1534 * <p> 1535 * There is no restriction on the value of {@code fromIndex}. If it 1536 * is negative, it has the same effect as if it were zero: this entire 1537 * string may be searched. If it is greater than the length of this 1538 * string, it has the same effect as if it were equal to the length of 1539 * this string: {@code -1} is returned. 1540 * 1541 * <p>All indices are specified in {@code char} values 1542 * (Unicode code units). 1543 * 1544 * @param ch a character (Unicode code point). 1545 * @param fromIndex the index to start the search from. 1546 * @return the index of the first occurrence of the character in the 1547 * character sequence represented by this object that is greater 1548 * than or equal to {@code fromIndex}, or {@code -1} 1549 * if the character does not occur. 1550 */ 1551 public int indexOf(int ch, int fromIndex) { 1552 final int max = value.length; 1553 if (fromIndex < 0) { 1554 fromIndex = 0; 1555 } else if (fromIndex >= max) { 1556 // Note: fromIndex might be near -1>>>1. 1557 return -1; 1558 } 1559 1560 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) { 1561 // handle most cases here (ch is a BMP code point or a 1562 // negative value (invalid code point)) 1563 final char[] value = this.value; 1564 for (int i = fromIndex; i < max; i++) { 1565 if (value[i] == ch) { 1566 return i; 1567 } 1568 } 1569 return -1; 1570 } else { 1571 return indexOfSupplementary(ch, fromIndex); 1572 } 1573 } 1574 1575 /** 1576 * Handles (rare) calls of indexOf with a supplementary character. 1577 */ 1578 private int indexOfSupplementary(int ch, int fromIndex) { 1579 if (Character.isValidCodePoint(ch)) { 1580 final char[] value = this.value; 1581 final char hi = Character.highSurrogate(ch); 1582 final char lo = Character.lowSurrogate(ch); 1583 final int max = value.length - 1; 1584 for (int i = fromIndex; i < max; i++) { 1585 if (value[i] == hi && value[i + 1] == lo) { 1586 return i; 1587 } 1588 } 1589 } 1590 return -1; 1591 } 1592 1593 /** 1594 * Returns the index within this string of the last occurrence of 1595 * the specified character. For values of {@code ch} in the 1596 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code 1597 * units) returned is the largest value <i>k</i> such that: 1598 * <blockquote><pre> 1599 * this.charAt(<i>k</i>) == ch 1600 * </pre></blockquote> 1601 * is true. For other values of {@code ch}, it is the 1602 * largest value <i>k</i> such that: 1603 * <blockquote><pre> 1604 * this.codePointAt(<i>k</i>) == ch 1605 * </pre></blockquote> 1606 * is true. In either case, if no such character occurs in this 1607 * string, then {@code -1} is returned. The 1608 * {@code String} is searched backwards starting at the last 1609 * character. 1610 * 1611 * @param ch a character (Unicode code point). 1612 * @return the index of the last occurrence of the character in the 1613 * character sequence represented by this object, or 1614 * {@code -1} if the character does not occur. 1615 */ 1616 public int lastIndexOf(int ch) { 1617 return lastIndexOf(ch, value.length - 1); 1618 } 1619 1620 /** 1621 * Returns the index within this string of the last occurrence of 1622 * the specified character, searching backward starting at the 1623 * specified index. For values of {@code ch} in the range 1624 * from 0 to 0xFFFF (inclusive), the index returned is the largest 1625 * value <i>k</i> such that: 1626 * <blockquote><pre> 1627 * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex) 1628 * </pre></blockquote> 1629 * is true. For other values of {@code ch}, it is the 1630 * largest value <i>k</i> such that: 1631 * <blockquote><pre> 1632 * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex) 1633 * </pre></blockquote> 1634 * is true. In either case, if no such character occurs in this 1635 * string at or before position {@code fromIndex}, then 1636 * {@code -1} is returned. 1637 * 1638 * <p>All indices are specified in {@code char} values 1639 * (Unicode code units). 1640 * 1641 * @param ch a character (Unicode code point). 1642 * @param fromIndex the index to start the search from. There is no 1643 * restriction on the value of {@code fromIndex}. If it is 1644 * greater than or equal to the length of this string, it has 1645 * the same effect as if it were equal to one less than the 1646 * length of this string: this entire string may be searched. 1647 * If it is negative, it has the same effect as if it were -1: 1648 * -1 is returned. 1649 * @return the index of the last occurrence of the character in the 1650 * character sequence represented by this object that is less 1651 * than or equal to {@code fromIndex}, or {@code -1} 1652 * if the character does not occur before that point. 1653 */ 1654 public int lastIndexOf(int ch, int fromIndex) { 1655 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) { 1656 // handle most cases here (ch is a BMP code point or a 1657 // negative value (invalid code point)) 1658 final char[] value = this.value; 1659 int i = Math.min(fromIndex, value.length - 1); 1660 for (; i >= 0; i--) { 1661 if (value[i] == ch) { 1662 return i; 1663 } 1664 } 1665 return -1; 1666 } else { 1667 return lastIndexOfSupplementary(ch, fromIndex); 1668 } 1669 } 1670 1671 /** 1672 * Handles (rare) calls of lastIndexOf with a supplementary character. 1673 */ 1674 private int lastIndexOfSupplementary(int ch, int fromIndex) { 1675 if (Character.isValidCodePoint(ch)) { 1676 final char[] value = this.value; 1677 char hi = Character.highSurrogate(ch); 1678 char lo = Character.lowSurrogate(ch); 1679 int i = Math.min(fromIndex, value.length - 2); 1680 for (; i >= 0; i--) { 1681 if (value[i] == hi && value[i + 1] == lo) { 1682 return i; 1683 } 1684 } 1685 } 1686 return -1; 1687 } 1688 1689 /** 1690 * Returns the index within this string of the first occurrence of the 1691 * specified substring. 1692 * 1693 * <p>The returned index is the smallest value {@code k} for which: 1694 * <pre>{@code 1695 * this.startsWith(str, k) 1696 * }</pre> 1697 * If no such value of {@code k} exists, then {@code -1} is returned. 1698 * 1699 * @param str the substring to search for. 1700 * @return the index of the first occurrence of the specified substring, 1701 * or {@code -1} if there is no such occurrence. 1702 */ 1703 @HotSpotIntrinsicCandidate 1704 public int indexOf(String str) { 1705 return indexOf(str, 0); 1706 } 1707 1708 /** 1709 * Returns the index within this string of the first occurrence of the 1710 * specified substring, starting at the specified index. 1711 * 1712 * <p>The returned index is the smallest value {@code k} for which: 1713 * <pre>{@code 1714 * k >= Math.min(fromIndex, this.length()) && 1715 * this.startsWith(str, k) 1716 * }</pre> 1717 * If no such value of {@code k} exists, then {@code -1} is returned. 1718 * 1719 * @param str the substring to search for. 1720 * @param fromIndex the index from which to start the search. 1721 * @return the index of the first occurrence of the specified substring, 1722 * starting at the specified index, 1723 * or {@code -1} if there is no such occurrence. 1724 */ 1725 public int indexOf(String str, int fromIndex) { 1726 return indexOf(value, 0, value.length, 1727 str.value, 0, str.value.length, fromIndex); 1728 } 1729 1730 /** 1731 * Code shared by String and AbstractStringBuilder to do searches. The 1732 * source is the character array being searched, and the target 1733 * is the string being searched for. 1734 * 1735 * @param source the characters being searched. 1736 * @param sourceOffset offset of the source string. 1737 * @param sourceCount count of the source string. 1738 * @param target the characters being searched for. 1739 * @param fromIndex the index to begin searching from. 1740 */ 1741 static int indexOf(char[] source, int sourceOffset, int sourceCount, 1742 String target, int fromIndex) { 1743 return indexOf(source, sourceOffset, sourceCount, 1744 target.value, 0, target.value.length, 1745 fromIndex); 1746 } 1747 1748 /** 1749 * Code shared by String and StringBuffer to do searches. The 1750 * source is the character array being searched, and the target 1751 * is the string being searched for. 1752 * 1753 * @param source the characters being searched. 1754 * @param sourceOffset offset of the source string. 1755 * @param sourceCount count of the source string. 1756 * @param target the characters being searched for. 1757 * @param targetOffset offset of the target string. 1758 * @param targetCount count of the target string. 1759 * @param fromIndex the index to begin searching from. 1760 */ 1761 static int indexOf(char[] source, int sourceOffset, int sourceCount, 1762 char[] target, int targetOffset, int targetCount, 1763 int fromIndex) { 1764 if (fromIndex >= sourceCount) { 1765 return (targetCount == 0 ? sourceCount : -1); 1766 } 1767 if (fromIndex < 0) { 1768 fromIndex = 0; 1769 } 1770 if (targetCount == 0) { 1771 return fromIndex; 1772 } 1773 1774 char first = target[targetOffset]; 1775 int max = sourceOffset + (sourceCount - targetCount); 1776 1777 for (int i = sourceOffset + fromIndex; i <= max; i++) { 1778 /* Look for first character. */ 1779 if (source[i] != first) { 1780 while (++i <= max && source[i] != first); 1781 } 1782 1783 /* Found first character, now look at the rest of v2 */ 1784 if (i <= max) { 1785 int j = i + 1; 1786 int end = j + targetCount - 1; 1787 for (int k = targetOffset + 1; j < end && source[j] 1788 == target[k]; j++, k++); 1789 1790 if (j == end) { 1791 /* Found whole string. */ 1792 return i - sourceOffset; 1793 } 1794 } 1795 } 1796 return -1; 1797 } 1798 1799 /** 1800 * Returns the index within this string of the last occurrence of the 1801 * specified substring. The last occurrence of the empty string "" 1802 * is considered to occur at the index value {@code this.length()}. 1803 * 1804 * <p>The returned index is the largest value {@code k} for which: 1805 * <pre>{@code 1806 * this.startsWith(str, k) 1807 * }</pre> 1808 * If no such value of {@code k} exists, then {@code -1} is returned. 1809 * 1810 * @param str the substring to search for. 1811 * @return the index of the last occurrence of the specified substring, 1812 * or {@code -1} if there is no such occurrence. 1813 */ 1814 public int lastIndexOf(String str) { 1815 return lastIndexOf(str, value.length); 1816 } 1817 1818 /** 1819 * Returns the index within this string of the last occurrence of the 1820 * specified substring, searching backward starting at the specified index. 1821 * 1822 * <p>The returned index is the largest value {@code k} for which: 1823 * <pre>{@code 1824 * k <= Math.min(fromIndex, this.length()) && 1825 * this.startsWith(str, k) 1826 * }</pre> 1827 * If no such value of {@code k} exists, then {@code -1} is returned. 1828 * 1829 * @param str the substring to search for. 1830 * @param fromIndex the index to start the search from. 1831 * @return the index of the last occurrence of the specified substring, 1832 * searching backward from the specified index, 1833 * or {@code -1} if there is no such occurrence. 1834 */ 1835 public int lastIndexOf(String str, int fromIndex) { 1836 return lastIndexOf(value, 0, value.length, 1837 str.value, 0, str.value.length, fromIndex); 1838 } 1839 1840 /** 1841 * Code shared by String and AbstractStringBuilder to do searches. The 1842 * source is the character array being searched, and the target 1843 * is the string being searched for. 1844 * 1845 * @param source the characters being searched. 1846 * @param sourceOffset offset of the source string. 1847 * @param sourceCount count of the source string. 1848 * @param target the characters being searched for. 1849 * @param fromIndex the index to begin searching from. 1850 */ 1851 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount, 1852 String target, int fromIndex) { 1853 return lastIndexOf(source, sourceOffset, sourceCount, 1854 target.value, 0, target.value.length, 1855 fromIndex); 1856 } 1857 1858 /** 1859 * Code shared by String and StringBuffer to do searches. The 1860 * source is the character array being searched, and the target 1861 * is the string being searched for. 1862 * 1863 * @param source the characters being searched. 1864 * @param sourceOffset offset of the source string. 1865 * @param sourceCount count of the source string. 1866 * @param target the characters being searched for. 1867 * @param targetOffset offset of the target string. 1868 * @param targetCount count of the target string. 1869 * @param fromIndex the index to begin searching from. 1870 */ 1871 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount, 1872 char[] target, int targetOffset, int targetCount, 1873 int fromIndex) { 1874 /* 1875 * Check arguments; return immediately where possible. For 1876 * consistency, don't check for null str. 1877 */ 1878 int rightIndex = sourceCount - targetCount; 1879 if (fromIndex < 0) { 1880 return -1; 1881 } 1882 if (fromIndex > rightIndex) { 1883 fromIndex = rightIndex; 1884 } 1885 /* Empty string always matches. */ 1886 if (targetCount == 0) { 1887 return fromIndex; 1888 } 1889 1890 int strLastIndex = targetOffset + targetCount - 1; 1891 char strLastChar = target[strLastIndex]; 1892 int min = sourceOffset + targetCount - 1; 1893 int i = min + fromIndex; 1894 1895 startSearchForLastChar: 1896 while (true) { 1897 while (i >= min && source[i] != strLastChar) { 1898 i--; 1899 } 1900 if (i < min) { 1901 return -1; 1902 } 1903 int j = i - 1; 1904 int start = j - (targetCount - 1); 1905 int k = strLastIndex - 1; 1906 1907 while (j > start) { 1908 if (source[j--] != target[k--]) { 1909 i--; 1910 continue startSearchForLastChar; 1911 } 1912 } 1913 return start - sourceOffset + 1; 1914 } 1915 } 1916 1917 /** 1918 * Returns a string that is a substring of this string. The 1919 * substring begins with the character at the specified index and 1920 * extends to the end of this string. <p> 1921 * Examples: 1922 * <blockquote><pre> 1923 * "unhappy".substring(2) returns "happy" 1924 * "Harbison".substring(3) returns "bison" 1925 * "emptiness".substring(9) returns "" (an empty string) 1926 * </pre></blockquote> 1927 * 1928 * @param beginIndex the beginning index, inclusive. 1929 * @return the specified substring. 1930 * @exception IndexOutOfBoundsException if 1931 * {@code beginIndex} is negative or larger than the 1932 * length of this {@code String} object. 1933 */ 1934 public String substring(int beginIndex) { 1935 if (beginIndex <= 0) { 1936 if (beginIndex < 0) { 1937 throw new StringIndexOutOfBoundsException(beginIndex); 1938 } 1939 return this; 1940 } 1941 int subLen = value.length - beginIndex; 1942 if (subLen < 0) { 1943 throw new StringIndexOutOfBoundsException(subLen); 1944 } 1945 return new String(value, beginIndex, subLen); 1946 } 1947 1948 /** 1949 * Returns a string that is a substring of this string. The 1950 * substring begins at the specified {@code beginIndex} and 1951 * extends to the character at index {@code endIndex - 1}. 1952 * Thus the length of the substring is {@code endIndex-beginIndex}. 1953 * <p> 1954 * Examples: 1955 * <blockquote><pre> 1956 * "hamburger".substring(4, 8) returns "urge" 1957 * "smiles".substring(1, 5) returns "mile" 1958 * </pre></blockquote> 1959 * 1960 * @param beginIndex the beginning index, inclusive. 1961 * @param endIndex the ending index, exclusive. 1962 * @return the specified substring. 1963 * @exception IndexOutOfBoundsException if the 1964 * {@code beginIndex} is negative, or 1965 * {@code endIndex} is larger than the length of 1966 * this {@code String} object, or 1967 * {@code beginIndex} is larger than 1968 * {@code endIndex}. 1969 */ 1970 public String substring(int beginIndex, int endIndex) { 1971 if (beginIndex <= 0) { 1972 if (beginIndex < 0) { 1973 throw new StringIndexOutOfBoundsException(beginIndex); 1974 } 1975 if (endIndex == value.length) { 1976 return this; 1977 } 1978 } 1979 if (endIndex > value.length) { 1980 throw new StringIndexOutOfBoundsException(endIndex); 1981 } 1982 int subLen = endIndex - beginIndex; 1983 if (subLen < 0) { 1984 throw new StringIndexOutOfBoundsException(subLen); 1985 } 1986 return new String(value, beginIndex, subLen); 1987 } 1988 1989 /** 1990 * Returns a character sequence that is a subsequence of this sequence. 1991 * 1992 * <p> An invocation of this method of the form 1993 * 1994 * <blockquote><pre> 1995 * str.subSequence(begin, end)</pre></blockquote> 1996 * 1997 * behaves in exactly the same way as the invocation 1998 * 1999 * <blockquote><pre> 2000 * str.substring(begin, end)</pre></blockquote> 2001 * 2002 * @apiNote 2003 * This method is defined so that the {@code String} class can implement 2004 * the {@link CharSequence} interface. 2005 * 2006 * @param beginIndex the begin index, inclusive. 2007 * @param endIndex the end index, exclusive. 2008 * @return the specified subsequence. 2009 * 2010 * @throws IndexOutOfBoundsException 2011 * if {@code beginIndex} or {@code endIndex} is negative, 2012 * if {@code endIndex} is greater than {@code length()}, 2013 * or if {@code beginIndex} is greater than {@code endIndex} 2014 * 2015 * @since 1.4 2016 * @spec JSR-51 2017 */ 2018 public CharSequence subSequence(int beginIndex, int endIndex) { 2019 return this.substring(beginIndex, endIndex); 2020 } 2021 2022 /** 2023 * Concatenates the specified string to the end of this string. 2024 * <p> 2025 * If the length of the argument string is {@code 0}, then this 2026 * {@code String} object is returned. Otherwise, a 2027 * {@code String} object is returned that represents a character 2028 * sequence that is the concatenation of the character sequence 2029 * represented by this {@code String} object and the character 2030 * sequence represented by the argument string.<p> 2031 * Examples: 2032 * <blockquote><pre> 2033 * "cares".concat("s") returns "caress" 2034 * "to".concat("get").concat("her") returns "together" 2035 * </pre></blockquote> 2036 * 2037 * @param str the {@code String} that is concatenated to the end 2038 * of this {@code String}. 2039 * @return a string that represents the concatenation of this object's 2040 * characters followed by the string argument's characters. 2041 */ 2042 public String concat(String str) { 2043 int otherLen = str.length(); 2044 if (otherLen == 0) { 2045 return this; 2046 } 2047 int len = value.length; 2048 char[] buf = Arrays.copyOf(value, len + otherLen); 2049 str.getChars(buf, len); 2050 return new String(buf, true); 2051 } 2052 2053 /** 2054 * Returns a string resulting from replacing all occurrences of 2055 * {@code oldChar} in this string with {@code newChar}. 2056 * <p> 2057 * If the character {@code oldChar} does not occur in the 2058 * character sequence represented by this {@code String} object, 2059 * then a reference to this {@code String} object is returned. 2060 * Otherwise, a {@code String} object is returned that 2061 * represents a character sequence identical to the character sequence 2062 * represented by this {@code String} object, except that every 2063 * occurrence of {@code oldChar} is replaced by an occurrence 2064 * of {@code newChar}. 2065 * <p> 2066 * Examples: 2067 * <blockquote><pre> 2068 * "mesquite in your cellar".replace('e', 'o') 2069 * returns "mosquito in your collar" 2070 * "the war of baronets".replace('r', 'y') 2071 * returns "the way of bayonets" 2072 * "sparring with a purple porpoise".replace('p', 't') 2073 * returns "starring with a turtle tortoise" 2074 * "JonL".replace('q', 'x') returns "JonL" (no change) 2075 * </pre></blockquote> 2076 * 2077 * @param oldChar the old character. 2078 * @param newChar the new character. 2079 * @return a string derived from this string by replacing every 2080 * occurrence of {@code oldChar} with {@code newChar}. 2081 */ 2082 public String replace(char oldChar, char newChar) { 2083 if (oldChar != newChar) { 2084 char[] val = value; /* avoid getfield opcode */ 2085 int len = val.length; 2086 int i = -1; 2087 2088 while (++i < len) { 2089 if (val[i] == oldChar) { 2090 break; 2091 } 2092 } 2093 if (i < len) { 2094 char[] buf = new char[len]; 2095 for (int j = 0; j < i; j++) { 2096 buf[j] = val[j]; 2097 } 2098 while (i < len) { 2099 char c = val[i]; 2100 buf[i] = (c == oldChar) ? newChar : c; 2101 i++; 2102 } 2103 return new String(buf, true); 2104 } 2105 } 2106 return this; 2107 } 2108 2109 /** 2110 * Tells whether or not this string matches the given <a 2111 * href="../util/regex/Pattern.html#sum">regular expression</a>. 2112 * 2113 * <p> An invocation of this method of the form 2114 * <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the 2115 * same result as the expression 2116 * 2117 * <blockquote> 2118 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#matches(String,CharSequence) 2119 * matches(<i>regex</i>, <i>str</i>)} 2120 * </blockquote> 2121 * 2122 * @param regex 2123 * the regular expression to which this string is to be matched 2124 * 2125 * @return {@code true} if, and only if, this string matches the 2126 * given regular expression 2127 * 2128 * @throws PatternSyntaxException 2129 * if the regular expression's syntax is invalid 2130 * 2131 * @see java.util.regex.Pattern 2132 * 2133 * @since 1.4 2134 * @spec JSR-51 2135 */ 2136 public boolean matches(String regex) { 2137 return Pattern.matches(regex, this); 2138 } 2139 2140 /** 2141 * Returns true if and only if this string contains the specified 2142 * sequence of char values. 2143 * 2144 * @param s the sequence to search for 2145 * @return true if this string contains {@code s}, false otherwise 2146 * @since 1.5 2147 */ 2148 public boolean contains(CharSequence s) { 2149 return indexOf(s.toString()) >= 0; 2150 } 2151 2152 /** 2153 * Replaces the first substring of this string that matches the given <a 2154 * href="../util/regex/Pattern.html#sum">regular expression</a> with the 2155 * given replacement. 2156 * 2157 * <p> An invocation of this method of the form 2158 * <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )} 2159 * yields exactly the same result as the expression 2160 * 2161 * <blockquote> 2162 * <code> 2163 * {@link java.util.regex.Pattern}.{@link 2164 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link 2165 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link 2166 * java.util.regex.Matcher#replaceFirst replaceFirst}(<i>repl</i>) 2167 * </code> 2168 * </blockquote> 2169 * 2170 *<p> 2171 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the 2172 * replacement string may cause the results to be different than if it were 2173 * being treated as a literal replacement string; see 2174 * {@link java.util.regex.Matcher#replaceFirst}. 2175 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special 2176 * meaning of these characters, if desired. 2177 * 2178 * @param regex 2179 * the regular expression to which this string is to be matched 2180 * @param replacement 2181 * the string to be substituted for the first match 2182 * 2183 * @return The resulting {@code String} 2184 * 2185 * @throws PatternSyntaxException 2186 * if the regular expression's syntax is invalid 2187 * 2188 * @see java.util.regex.Pattern 2189 * 2190 * @since 1.4 2191 * @spec JSR-51 2192 */ 2193 public String replaceFirst(String regex, String replacement) { 2194 return Pattern.compile(regex).matcher(this).replaceFirst(replacement); 2195 } 2196 2197 /** 2198 * Replaces each substring of this string that matches the given <a 2199 * href="../util/regex/Pattern.html#sum">regular expression</a> with the 2200 * given replacement. 2201 * 2202 * <p> An invocation of this method of the form 2203 * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )} 2204 * yields exactly the same result as the expression 2205 * 2206 * <blockquote> 2207 * <code> 2208 * {@link java.util.regex.Pattern}.{@link 2209 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link 2210 * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link 2211 * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>) 2212 * </code> 2213 * </blockquote> 2214 * 2215 *<p> 2216 * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the 2217 * replacement string may cause the results to be different than if it were 2218 * being treated as a literal replacement string; see 2219 * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}. 2220 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special 2221 * meaning of these characters, if desired. 2222 * 2223 * @param regex 2224 * the regular expression to which this string is to be matched 2225 * @param replacement 2226 * the string to be substituted for each match 2227 * 2228 * @return The resulting {@code String} 2229 * 2230 * @throws PatternSyntaxException 2231 * if the regular expression's syntax is invalid 2232 * 2233 * @see java.util.regex.Pattern 2234 * 2235 * @since 1.4 2236 * @spec JSR-51 2237 */ 2238 public String replaceAll(String regex, String replacement) { 2239 return Pattern.compile(regex).matcher(this).replaceAll(replacement); 2240 } 2241 2242 /** 2243 * Replaces each substring of this string that matches the literal target 2244 * sequence with the specified literal replacement sequence. The 2245 * replacement proceeds from the beginning of the string to the end, for 2246 * example, replacing "aa" with "b" in the string "aaa" will result in 2247 * "ba" rather than "ab". 2248 * 2249 * @param target The sequence of char values to be replaced 2250 * @param replacement The replacement sequence of char values 2251 * @return The resulting string 2252 * @since 1.5 2253 */ 2254 public String replace(CharSequence target, CharSequence replacement) { 2255 String starget = target.toString(); 2256 String srepl = replacement.toString(); 2257 int j = indexOf(starget); 2258 if (j < 0) { 2259 return this; 2260 } 2261 int targLen = starget.length(); 2262 int targLen1 = Math.max(targLen, 1); 2263 final char[] value = this.value; 2264 final char[] replValue = srepl.value; 2265 int newLenHint = value.length - targLen + replValue.length; 2266 if (newLenHint < 0) { 2267 throw new OutOfMemoryError(); 2268 } 2269 StringBuilder sb = new StringBuilder(newLenHint); 2270 int i = 0; 2271 do { 2272 sb.append(value, i, j - i) 2273 .append(replValue); 2274 i = j + targLen; 2275 } while (j < value.length && (j = indexOf(starget, j + targLen1)) > 0); 2276 2277 return sb.append(value, i, value.length - i).toString(); 2278 } 2279 2280 /** 2281 * Splits this string around matches of the given 2282 * <a href="../util/regex/Pattern.html#sum">regular expression</a>. 2283 * 2284 * <p> The array returned by this method contains each substring of this 2285 * string that is terminated by another substring that matches the given 2286 * expression or is terminated by the end of the string. The substrings in 2287 * the array are in the order in which they occur in this string. If the 2288 * expression does not match any part of the input then the resulting array 2289 * has just one element, namely this string. 2290 * 2291 * <p> When there is a positive-width match at the beginning of this 2292 * string then an empty leading substring is included at the beginning 2293 * of the resulting array. A zero-width match at the beginning however 2294 * never produces such empty leading substring. 2295 * 2296 * <p> The {@code limit} parameter controls the number of times the 2297 * pattern is applied and therefore affects the length of the resulting 2298 * array. If the limit <i>n</i> is greater than zero then the pattern 2299 * will be applied at most <i>n</i> - 1 times, the array's 2300 * length will be no greater than <i>n</i>, and the array's last entry 2301 * will contain all input beyond the last matched delimiter. If <i>n</i> 2302 * is non-positive then the pattern will be applied as many times as 2303 * possible and the array can have any length. If <i>n</i> is zero then 2304 * the pattern will be applied as many times as possible, the array can 2305 * have any length, and trailing empty strings will be discarded. 2306 * 2307 * <p> The string {@code "boo:and:foo"}, for example, yields the 2308 * following results with these parameters: 2309 * 2310 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split example showing regex, limit, and result"> 2311 * <tr> 2312 * <th>Regex</th> 2313 * <th>Limit</th> 2314 * <th>Result</th> 2315 * </tr> 2316 * <tr><td align=center>:</td> 2317 * <td align=center>2</td> 2318 * <td>{@code { "boo", "and:foo" }}</td></tr> 2319 * <tr><td align=center>:</td> 2320 * <td align=center>5</td> 2321 * <td>{@code { "boo", "and", "foo" }}</td></tr> 2322 * <tr><td align=center>:</td> 2323 * <td align=center>-2</td> 2324 * <td>{@code { "boo", "and", "foo" }}</td></tr> 2325 * <tr><td align=center>o</td> 2326 * <td align=center>5</td> 2327 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr> 2328 * <tr><td align=center>o</td> 2329 * <td align=center>-2</td> 2330 * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr> 2331 * <tr><td align=center>o</td> 2332 * <td align=center>0</td> 2333 * <td>{@code { "b", "", ":and:f" }}</td></tr> 2334 * </table></blockquote> 2335 * 2336 * <p> An invocation of this method of the form 2337 * <i>str.</i>{@code split(}<i>regex</i>{@code ,} <i>n</i>{@code )} 2338 * yields the same result as the expression 2339 * 2340 * <blockquote> 2341 * <code> 2342 * {@link java.util.regex.Pattern}.{@link 2343 * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link 2344 * java.util.regex.Pattern#split(java.lang.CharSequence,int) split}(<i>str</i>, <i>n</i>) 2345 * </code> 2346 * </blockquote> 2347 * 2348 * 2349 * @param regex 2350 * the delimiting regular expression 2351 * 2352 * @param limit 2353 * the result threshold, as described above 2354 * 2355 * @return the array of strings computed by splitting this string 2356 * around matches of the given regular expression 2357 * 2358 * @throws PatternSyntaxException 2359 * if the regular expression's syntax is invalid 2360 * 2361 * @see java.util.regex.Pattern 2362 * 2363 * @since 1.4 2364 * @spec JSR-51 2365 */ 2366 public String[] split(String regex, int limit) { 2367 /* fastpath if the regex is a 2368 (1)one-char String and this character is not one of the 2369 RegEx's meta characters ".$|()[{^?*+\\", or 2370 (2)two-char String and the first char is the backslash and 2371 the second is not the ascii digit or ascii letter. 2372 */ 2373 char ch = 0; 2374 if (((regex.value.length == 1 && 2375 ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) || 2376 (regex.length() == 2 && 2377 regex.charAt(0) == '\\' && 2378 (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 && 2379 ((ch-'a')|('z'-ch)) < 0 && 2380 ((ch-'A')|('Z'-ch)) < 0)) && 2381 (ch < Character.MIN_HIGH_SURROGATE || 2382 ch > Character.MAX_LOW_SURROGATE)) 2383 { 2384 int off = 0; 2385 int next = 0; 2386 boolean limited = limit > 0; 2387 ArrayList<String> list = new ArrayList<>(); 2388 while ((next = indexOf(ch, off)) != -1) { 2389 if (!limited || list.size() < limit - 1) { 2390 list.add(substring(off, next)); 2391 off = next + 1; 2392 } else { // last one 2393 //assert (list.size() == limit - 1); 2394 list.add(substring(off, value.length)); 2395 off = value.length; 2396 break; 2397 } 2398 } 2399 // If no match was found, return this 2400 if (off == 0) 2401 return new String[]{this}; 2402 2403 // Add remaining segment 2404 if (!limited || list.size() < limit) 2405 list.add(substring(off, value.length)); 2406 2407 // Construct result 2408 int resultSize = list.size(); 2409 if (limit == 0) { 2410 while (resultSize > 0 && list.get(resultSize - 1).length() == 0) { 2411 resultSize--; 2412 } 2413 } 2414 String[] result = new String[resultSize]; 2415 return list.subList(0, resultSize).toArray(result); 2416 } 2417 return Pattern.compile(regex).split(this, limit); 2418 } 2419 2420 /** 2421 * Splits this string around matches of the given <a 2422 * href="../util/regex/Pattern.html#sum">regular expression</a>. 2423 * 2424 * <p> This method works as if by invoking the two-argument {@link 2425 * #split(String, int) split} method with the given expression and a limit 2426 * argument of zero. Trailing empty strings are therefore not included in 2427 * the resulting array. 2428 * 2429 * <p> The string {@code "boo:and:foo"}, for example, yields the following 2430 * results with these expressions: 2431 * 2432 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split examples showing regex and result"> 2433 * <tr> 2434 * <th>Regex</th> 2435 * <th>Result</th> 2436 * </tr> 2437 * <tr><td align=center>:</td> 2438 * <td>{@code { "boo", "and", "foo" }}</td></tr> 2439 * <tr><td align=center>o</td> 2440 * <td>{@code { "b", "", ":and:f" }}</td></tr> 2441 * </table></blockquote> 2442 * 2443 * 2444 * @param regex 2445 * the delimiting regular expression 2446 * 2447 * @return the array of strings computed by splitting this string 2448 * around matches of the given regular expression 2449 * 2450 * @throws PatternSyntaxException 2451 * if the regular expression's syntax is invalid 2452 * 2453 * @see java.util.regex.Pattern 2454 * 2455 * @since 1.4 2456 * @spec JSR-51 2457 */ 2458 public String[] split(String regex) { 2459 return split(regex, 0); 2460 } 2461 2462 /** 2463 * Returns a new String composed of copies of the 2464 * {@code CharSequence elements} joined together with a copy of 2465 * the specified {@code delimiter}. 2466 * 2467 * <blockquote>For example, 2468 * <pre>{@code 2469 * String message = String.join("-", "Java", "is", "cool"); 2470 * // message returned is: "Java-is-cool" 2471 * }</pre></blockquote> 2472 * 2473 * Note that if an element is null, then {@code "null"} is added. 2474 * 2475 * @param delimiter the delimiter that separates each element 2476 * @param elements the elements to join together. 2477 * 2478 * @return a new {@code String} that is composed of the {@code elements} 2479 * separated by the {@code delimiter} 2480 * 2481 * @throws NullPointerException If {@code delimiter} or {@code elements} 2482 * is {@code null} 2483 * 2484 * @see java.util.StringJoiner 2485 * @since 1.8 2486 */ 2487 public static String join(CharSequence delimiter, CharSequence... elements) { 2488 Objects.requireNonNull(delimiter); 2489 Objects.requireNonNull(elements); 2490 // Number of elements not likely worth Arrays.stream overhead. 2491 StringJoiner joiner = new StringJoiner(delimiter); 2492 for (CharSequence cs: elements) { 2493 joiner.add(cs); 2494 } 2495 return joiner.toString(); 2496 } 2497 2498 /** 2499 * Returns a new {@code String} composed of copies of the 2500 * {@code CharSequence elements} joined together with a copy of the 2501 * specified {@code delimiter}. 2502 * 2503 * <blockquote>For example, 2504 * <pre>{@code 2505 * List<String> strings = new LinkedList<>(); 2506 * strings.add("Java");strings.add("is"); 2507 * strings.add("cool"); 2508 * String message = String.join(" ", strings); 2509 * //message returned is: "Java is cool" 2510 * 2511 * Set<String> strings = new LinkedHashSet<>(); 2512 * strings.add("Java"); strings.add("is"); 2513 * strings.add("very"); strings.add("cool"); 2514 * String message = String.join("-", strings); 2515 * //message returned is: "Java-is-very-cool" 2516 * }</pre></blockquote> 2517 * 2518 * Note that if an individual element is {@code null}, then {@code "null"} is added. 2519 * 2520 * @param delimiter a sequence of characters that is used to separate each 2521 * of the {@code elements} in the resulting {@code String} 2522 * @param elements an {@code Iterable} that will have its {@code elements} 2523 * joined together. 2524 * 2525 * @return a new {@code String} that is composed from the {@code elements} 2526 * argument 2527 * 2528 * @throws NullPointerException If {@code delimiter} or {@code elements} 2529 * is {@code null} 2530 * 2531 * @see #join(CharSequence,CharSequence...) 2532 * @see java.util.StringJoiner 2533 * @since 1.8 2534 */ 2535 public static String join(CharSequence delimiter, 2536 Iterable<? extends CharSequence> elements) { 2537 Objects.requireNonNull(delimiter); 2538 Objects.requireNonNull(elements); 2539 StringJoiner joiner = new StringJoiner(delimiter); 2540 for (CharSequence cs: elements) { 2541 joiner.add(cs); 2542 } 2543 return joiner.toString(); 2544 } 2545 2546 /** 2547 * Converts all of the characters in this {@code String} to lower 2548 * case using the rules of the given {@code Locale}. Case mapping is based 2549 * on the Unicode Standard version specified by the {@link java.lang.Character Character} 2550 * class. Since case mappings are not always 1:1 char mappings, the resulting 2551 * {@code String} may be a different length than the original {@code String}. 2552 * <p> 2553 * Examples of lowercase mappings are in the following table: 2554 * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description"> 2555 * <tr> 2556 * <th>Language Code of Locale</th> 2557 * <th>Upper Case</th> 2558 * <th>Lower Case</th> 2559 * <th>Description</th> 2560 * </tr> 2561 * <tr> 2562 * <td>tr (Turkish)</td> 2563 * <td>\u0130</td> 2564 * <td>\u0069</td> 2565 * <td>capital letter I with dot above -> small letter i</td> 2566 * </tr> 2567 * <tr> 2568 * <td>tr (Turkish)</td> 2569 * <td>\u0049</td> 2570 * <td>\u0131</td> 2571 * <td>capital letter I -> small letter dotless i </td> 2572 * </tr> 2573 * <tr> 2574 * <td>(all)</td> 2575 * <td>French Fries</td> 2576 * <td>french fries</td> 2577 * <td>lowercased all chars in String</td> 2578 * </tr> 2579 * <tr> 2580 * <td>(all)</td> 2581 * <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi"> 2582 * <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil"> 2583 * <img src="doc-files/capsigma.gif" alt="capsigma"></td> 2584 * <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi"> 2585 * <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon"> 2586 * <img src="doc-files/sigma1.gif" alt="sigma"></td> 2587 * <td>lowercased all chars in String</td> 2588 * </tr> 2589 * </table> 2590 * 2591 * @param locale use the case transformation rules for this locale 2592 * @return the {@code String}, converted to lowercase. 2593 * @see java.lang.String#toLowerCase() 2594 * @see java.lang.String#toUpperCase() 2595 * @see java.lang.String#toUpperCase(Locale) 2596 * @since 1.1 2597 */ 2598 public String toLowerCase(Locale locale) { 2599 if (locale == null) { 2600 throw new NullPointerException(); 2601 } 2602 int first; 2603 boolean hasSurr = false; 2604 final int len = value.length; 2605 2606 // Now check if there are any characters that need to be changed, or are surrogate 2607 for (first = 0 ; first < len; first++) { 2608 int cp = (int)value[first]; 2609 if (Character.isSurrogate((char)cp)) { 2610 hasSurr = true; 2611 break; 2612 } 2613 if (cp != Character.toLowerCase(cp)) { // no need to check Character.ERROR 2614 break; 2615 } 2616 } 2617 if (first == len) 2618 return this; 2619 char[] result = new char[len]; 2620 System.arraycopy(value, 0, result, 0, first); // Just copy the first few 2621 // lowerCase characters. 2622 String lang = locale.getLanguage(); 2623 if (lang == "tr" || lang == "az" || lang == "lt") { 2624 return toLowerCaseEx(result, first, locale, true); 2625 } 2626 if (hasSurr) { 2627 return toLowerCaseEx(result, first, locale, false); 2628 } 2629 for (int i = first; i < len; i++) { 2630 int cp = (int)value[i]; 2631 if (cp == '\u03A3' || // GREEK CAPITAL LETTER SIGMA 2632 Character.isSurrogate((char)cp)) { 2633 return toLowerCaseEx(result, i, locale, false); 2634 } 2635 if (cp == '\u0130') { // LATIN CAPITAL LETTER I WITH DOT ABOVE 2636 return toLowerCaseEx(result, i, locale, true); 2637 } 2638 cp = Character.toLowerCase(cp); 2639 if (!Character.isBmpCodePoint(cp)) { 2640 return toLowerCaseEx(result, i, locale, false); 2641 } 2642 result[i] = (char)cp; 2643 } 2644 return new String(result, true); 2645 } 2646 2647 private String toLowerCaseEx(char[] result, int first, Locale locale, boolean localeDependent) { 2648 int resultOffset = first; 2649 int srcCount; 2650 for (int i = first; i < value.length; i += srcCount) { 2651 int srcChar = (int)value[i]; 2652 int lowerChar; 2653 char[] lowerCharArray; 2654 srcCount = 1; 2655 if (Character.isSurrogate((char)srcChar)) { 2656 srcChar = codePointAt(i); 2657 srcCount = Character.charCount(srcChar); 2658 } 2659 if (localeDependent || srcChar == '\u03A3') { // GREEK CAPITAL LETTER SIGMA 2660 lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale); 2661 } else { 2662 lowerChar = Character.toLowerCase(srcChar); 2663 } 2664 if (Character.isBmpCodePoint(lowerChar)) { // Character.ERROR is not a bmp 2665 result[resultOffset++] = (char)lowerChar; 2666 } else { 2667 if (lowerChar == Character.ERROR) { 2668 lowerCharArray = ConditionalSpecialCasing.toLowerCaseCharArray(this, i, locale); 2669 } else if (srcCount == 2) { 2670 resultOffset += Character.toChars(lowerChar, result, resultOffset); 2671 continue; 2672 } else { 2673 lowerCharArray = Character.toChars(lowerChar); 2674 } 2675 /* Grow result if needed */ 2676 int mapLen = lowerCharArray.length; 2677 if (mapLen > srcCount) { 2678 char[] result2 = new char[result.length + mapLen - srcCount]; 2679 System.arraycopy(result, 0, result2, 0, resultOffset); 2680 result = result2; 2681 } 2682 for (int x = 0; x < mapLen; ++x) { 2683 result[resultOffset++] = lowerCharArray[x]; 2684 } 2685 } 2686 } 2687 return new String(result, 0, resultOffset); 2688 } 2689 2690 /** 2691 * Converts all of the characters in this {@code String} to lower 2692 * case using the rules of the default locale. This is equivalent to calling 2693 * {@code toLowerCase(Locale.getDefault())}. 2694 * <p> 2695 * <b>Note:</b> This method is locale sensitive, and may produce unexpected 2696 * results if used for strings that are intended to be interpreted locale 2697 * independently. 2698 * Examples are programming language identifiers, protocol keys, and HTML 2699 * tags. 2700 * For instance, {@code "TITLE".toLowerCase()} in a Turkish locale 2701 * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the 2702 * LATIN SMALL LETTER DOTLESS I character. 2703 * To obtain correct results for locale insensitive strings, use 2704 * {@code toLowerCase(Locale.ROOT)}. 2705 * 2706 * @return the {@code String}, converted to lowercase. 2707 * @see java.lang.String#toLowerCase(Locale) 2708 */ 2709 public String toLowerCase() { 2710 return toLowerCase(Locale.getDefault()); 2711 } 2712 2713 /** 2714 * Converts all of the characters in this {@code String} to upper 2715 * case using the rules of the given {@code Locale}. Case mapping is based 2716 * on the Unicode Standard version specified by the {@link java.lang.Character Character} 2717 * class. Since case mappings are not always 1:1 char mappings, the resulting 2718 * {@code String} may be a different length than the original {@code String}. 2719 * <p> 2720 * Examples of locale-sensitive and 1:M case mappings are in the following table. 2721 * 2722 * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description."> 2723 * <tr> 2724 * <th>Language Code of Locale</th> 2725 * <th>Lower Case</th> 2726 * <th>Upper Case</th> 2727 * <th>Description</th> 2728 * </tr> 2729 * <tr> 2730 * <td>tr (Turkish)</td> 2731 * <td>\u0069</td> 2732 * <td>\u0130</td> 2733 * <td>small letter i -> capital letter I with dot above</td> 2734 * </tr> 2735 * <tr> 2736 * <td>tr (Turkish)</td> 2737 * <td>\u0131</td> 2738 * <td>\u0049</td> 2739 * <td>small letter dotless i -> capital letter I</td> 2740 * </tr> 2741 * <tr> 2742 * <td>(all)</td> 2743 * <td>\u00df</td> 2744 * <td>\u0053 \u0053</td> 2745 * <td>small letter sharp s -> two letters: SS</td> 2746 * </tr> 2747 * <tr> 2748 * <td>(all)</td> 2749 * <td>Fahrvergnügen</td> 2750 * <td>FAHRVERGNÜGEN</td> 2751 * <td></td> 2752 * </tr> 2753 * </table> 2754 * @param locale use the case transformation rules for this locale 2755 * @return the {@code String}, converted to uppercase. 2756 * @see java.lang.String#toUpperCase() 2757 * @see java.lang.String#toLowerCase() 2758 * @see java.lang.String#toLowerCase(Locale) 2759 * @since 1.1 2760 */ 2761 public String toUpperCase(Locale locale) { 2762 if (locale == null) { 2763 throw new NullPointerException(); 2764 } 2765 int first; 2766 boolean hasSurr = false; 2767 final int len = value.length; 2768 2769 // Now check if there are any characters that need to be changed, or are surrogate 2770 for (first = 0 ; first < len; first++ ) { 2771 int cp = (int)value[first]; 2772 if (Character.isSurrogate((char)cp)) { 2773 hasSurr = true; 2774 break; 2775 } 2776 if (cp != Character.toUpperCaseEx(cp)) { // no need to check Character.ERROR 2777 break; 2778 } 2779 } 2780 if (first == len) { 2781 return this; 2782 } 2783 char[] result = new char[len]; 2784 System.arraycopy(value, 0, result, 0, first); // Just copy the first few 2785 // upperCase characters. 2786 String lang = locale.getLanguage(); 2787 if (lang == "tr" || lang == "az" || lang == "lt") { 2788 return toUpperCaseEx(result, first, locale, true); 2789 } 2790 if (hasSurr) { 2791 return toUpperCaseEx(result, first, locale, false); 2792 } 2793 for (int i = first; i < len; i++) { 2794 int cp = (int)value[i]; 2795 if (Character.isSurrogate((char)cp)) { 2796 return toUpperCaseEx(result, i, locale, false); 2797 } 2798 cp = Character.toUpperCaseEx(cp); 2799 if (!Character.isBmpCodePoint(cp)) { // Character.ERROR is not bmp 2800 return toUpperCaseEx(result, i, locale, false); 2801 } 2802 result[i] = (char)cp; 2803 } 2804 return new String(result, true); 2805 } 2806 2807 private String toUpperCaseEx(char[] result, int first, Locale locale, 2808 boolean localeDependent) { 2809 int resultOffset = first; 2810 int srcCount; 2811 for (int i = first; i < value.length; i += srcCount) { 2812 int srcChar = (int)value[i]; 2813 int upperChar; 2814 char[] upperCharArray; 2815 srcCount = 1; 2816 if (Character.isSurrogate((char)srcChar)) { 2817 srcChar = codePointAt(i); 2818 srcCount = Character.charCount(srcChar); 2819 } 2820 if (localeDependent) { 2821 upperChar = ConditionalSpecialCasing.toUpperCaseEx(this, i, locale); 2822 } else { 2823 upperChar = Character.toUpperCaseEx(srcChar); 2824 } 2825 if (Character.isBmpCodePoint(upperChar)) { 2826 result[resultOffset++] = (char)upperChar; 2827 } else { 2828 if (upperChar == Character.ERROR) { 2829 if (localeDependent) { 2830 upperCharArray = 2831 ConditionalSpecialCasing.toUpperCaseCharArray(this, i, locale); 2832 } else { 2833 upperCharArray = Character.toUpperCaseCharArray(srcChar); 2834 } 2835 } else if (srcCount == 2) { 2836 resultOffset += Character.toChars(upperChar, result, resultOffset); 2837 continue; 2838 } else { 2839 upperCharArray = Character.toChars(upperChar); 2840 } 2841 /* Grow result if needed */ 2842 int mapLen = upperCharArray.length; 2843 if (mapLen > srcCount) { 2844 char[] result2 = new char[result.length + mapLen - srcCount]; 2845 System.arraycopy(result, 0, result2, 0, resultOffset); 2846 result = result2; 2847 } 2848 for (int x = 0; x < mapLen; ++x) { 2849 result[resultOffset++] = upperCharArray[x]; 2850 } 2851 } 2852 } 2853 return new String(result, 0, resultOffset); 2854 } 2855 2856 /** 2857 * Converts all of the characters in this {@code String} to upper 2858 * case using the rules of the default locale. This method is equivalent to 2859 * {@code toUpperCase(Locale.getDefault())}. 2860 * <p> 2861 * <b>Note:</b> This method is locale sensitive, and may produce unexpected 2862 * results if used for strings that are intended to be interpreted locale 2863 * independently. 2864 * Examples are programming language identifiers, protocol keys, and HTML 2865 * tags. 2866 * For instance, {@code "title".toUpperCase()} in a Turkish locale 2867 * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the 2868 * LATIN CAPITAL LETTER I WITH DOT ABOVE character. 2869 * To obtain correct results for locale insensitive strings, use 2870 * {@code toUpperCase(Locale.ROOT)}. 2871 * 2872 * @return the {@code String}, converted to uppercase. 2873 * @see java.lang.String#toUpperCase(Locale) 2874 */ 2875 public String toUpperCase() { 2876 return toUpperCase(Locale.getDefault()); 2877 } 2878 2879 /** 2880 * Returns a string whose value is this string, with any leading and trailing 2881 * whitespace removed. 2882 * <p> 2883 * If this {@code String} object represents an empty character 2884 * sequence, or the first and last characters of character sequence 2885 * represented by this {@code String} object both have codes 2886 * greater than {@code '\u005Cu0020'} (the space character), then a 2887 * reference to this {@code String} object is returned. 2888 * <p> 2889 * Otherwise, if there is no character with a code greater than 2890 * {@code '\u005Cu0020'} in the string, then a 2891 * {@code String} object representing an empty string is 2892 * returned. 2893 * <p> 2894 * Otherwise, let <i>k</i> be the index of the first character in the 2895 * string whose code is greater than {@code '\u005Cu0020'}, and let 2896 * <i>m</i> be the index of the last character in the string whose code 2897 * is greater than {@code '\u005Cu0020'}. A {@code String} 2898 * object is returned, representing the substring of this string that 2899 * begins with the character at index <i>k</i> and ends with the 2900 * character at index <i>m</i>-that is, the result of 2901 * {@code this.substring(k, m + 1)}. 2902 * <p> 2903 * This method may be used to trim whitespace (as defined above) from 2904 * the beginning and end of a string. 2905 * 2906 * @return A string whose value is this string, with any leading and trailing white 2907 * space removed, or this string if it has no leading or 2908 * trailing white space. 2909 */ 2910 public String trim() { 2911 char[] val = value; /* avoid getfield opcode */ 2912 int end = val.length; 2913 int beg = 0; 2914 2915 while ((beg < end) && (val[beg] <= ' ')) { 2916 beg++; 2917 } 2918 while ((beg < end) && (val[end - 1] <= ' ')) { 2919 end--; 2920 } 2921 return substring(beg, end); 2922 } 2923 2924 /** 2925 * This object (which is already a string!) is itself returned. 2926 * 2927 * @return the string itself. 2928 */ 2929 public String toString() { 2930 return this; 2931 } 2932 2933 static class IntCharArraySpliterator implements Spliterator.OfInt { 2934 private final char[] array; 2935 private int index; // current index, modified on advance/split 2936 private final int fence; // one past last index 2937 private final int cs; 2938 2939 IntCharArraySpliterator(char[] array, int acs) { 2940 this(array, 0, array.length, acs); 2941 } 2942 2943 IntCharArraySpliterator(char[] array, int origin, int fence, int acs) { 2944 this.array = array; 2945 this.index = origin; 2946 this.fence = fence; 2947 this.cs = acs | Spliterator.ORDERED | Spliterator.SIZED 2948 | Spliterator.SUBSIZED; 2949 } 2950 2951 @Override 2952 public OfInt trySplit() { 2953 int lo = index, mid = (lo + fence) >>> 1; 2954 return (lo >= mid) 2955 ? null 2956 : new IntCharArraySpliterator(array, lo, index = mid, cs); 2957 } 2958 2959 @Override 2960 public void forEachRemaining(IntConsumer action) { 2961 char[] a; int i, hi; // hoist accesses and checks from loop 2962 if (action == null) 2963 throw new NullPointerException(); 2964 if ((a = array).length >= (hi = fence) && 2965 (i = index) >= 0 && i < (index = hi)) { 2966 do { action.accept(a[i]); } while (++i < hi); 2967 } 2968 } 2969 2970 @Override 2971 public boolean tryAdvance(IntConsumer action) { 2972 if (action == null) 2973 throw new NullPointerException(); 2974 if (index >= 0 && index < fence) { 2975 action.accept(array[index++]); 2976 return true; 2977 } 2978 return false; 2979 } 2980 2981 @Override 2982 public long estimateSize() { return (long)(fence - index); } 2983 2984 @Override 2985 public int characteristics() { 2986 return cs; 2987 } 2988 } 2989 2990 /** 2991 * Returns a stream of {@code int} zero-extending the {@code char} values 2992 * from this sequence. Any char which maps to a <a 2993 * href="{@docRoot}/java/lang/Character.html#unicode">surrogate code 2994 * point</a> is passed through uninterpreted. 2995 * 2996 * @return an IntStream of char values from this sequence 2997 * @since 1.9 2998 */ 2999 @Override 3000 public IntStream chars() { 3001 return StreamSupport.intStream( 3002 new IntCharArraySpliterator(value, Spliterator.IMMUTABLE), false); 3003 } 3004 3005 static class CodePointsSpliterator implements Spliterator.OfInt { 3006 private final char[] array; 3007 private int index; // current index, modified on advance/split 3008 private final int fence; // one past last index 3009 private final int cs; 3010 3011 CodePointsSpliterator(char[] array, int acs) { 3012 this(array, 0, array.length, acs); 3013 } 3014 3015 CodePointsSpliterator(char[] array, int origin, int fence, int acs) { 3016 this.array = array; 3017 this.index = origin; 3018 this.fence = fence; 3019 this.cs = acs | Spliterator.ORDERED; 3020 } 3021 3022 @Override 3023 public OfInt trySplit() { 3024 int lo = index, mid = (lo + fence) >>> 1; 3025 if (lo >= mid) 3026 return null; 3027 3028 int midOneLess; 3029 // If the mid-point intersects a surrogate pair 3030 if (Character.isLowSurrogate(array[mid]) && 3031 Character.isHighSurrogate(array[midOneLess = (mid -1)])) { 3032 // If there is only one pair it cannot be split 3033 if (lo >= midOneLess) 3034 return null; 3035 // Shift the mid-point to align with the surrogate pair 3036 return new CodePointsSpliterator(array, lo, index = midOneLess, cs); 3037 } 3038 return new CodePointsSpliterator(array, lo, index = mid, cs); 3039 } 3040 3041 @Override 3042 public void forEachRemaining(IntConsumer action) { 3043 char[] a; int i, hi; // hoist accesses and checks from loop 3044 if (action == null) 3045 throw new NullPointerException(); 3046 if ((a = array).length >= (hi = fence) && 3047 (i = index) >= 0 && i < (index = hi)) { 3048 do { 3049 i = advance(a, i, hi, action); 3050 } while (i < hi); 3051 } 3052 } 3053 3054 @Override 3055 public boolean tryAdvance(IntConsumer action) { 3056 if (action == null) 3057 throw new NullPointerException(); 3058 if (index >= 0 && index < fence) { 3059 index = advance(array, index, fence, action); 3060 return true; 3061 } 3062 return false; 3063 } 3064 3065 // Advance one code point from the index, i, and return the next 3066 // index to advance from 3067 private static int advance(char[] a, int i, int hi, IntConsumer action) { 3068 char c1 = a[i++]; 3069 int cp = c1; 3070 if (Character.isHighSurrogate(c1) && i < hi) { 3071 char c2 = a[i]; 3072 if (Character.isLowSurrogate(c2)) { 3073 i++; 3074 cp = Character.toCodePoint(c1, c2); 3075 } 3076 } 3077 action.accept(cp); 3078 return i; 3079 } 3080 3081 @Override 3082 public long estimateSize() { return (long)(fence - index); } 3083 3084 @Override 3085 public int characteristics() { 3086 return cs; 3087 } 3088 } 3089 3090 /** 3091 * Returns a stream of code point values from this sequence. Any surrogate 3092 * pairs encountered in the sequence are combined as if by {@linkplain 3093 * Character#toCodePoint Character.toCodePoint} and the result is passed 3094 * to the stream. Any other code units, including ordinary BMP characters, 3095 * unpaired surrogates, and undefined code units, are zero-extended to 3096 * {@code int} values which are then passed to the stream. 3097 * 3098 * @return an IntStream of Unicode code points from this sequence 3099 * @since 1.9 3100 */ 3101 @Override 3102 public IntStream codePoints() { 3103 return StreamSupport.intStream( 3104 new CodePointsSpliterator(value, Spliterator.IMMUTABLE), false); 3105 } 3106 3107 /** 3108 * Converts this string to a new character array. 3109 * 3110 * @return a newly allocated character array whose length is the length 3111 * of this string and whose contents are initialized to contain 3112 * the character sequence represented by this string. 3113 */ 3114 public char[] toCharArray() { 3115 // Cannot use Arrays.copyOf because of class initialization order issues 3116 char[] result = new char[value.length]; 3117 System.arraycopy(value, 0, result, 0, value.length); 3118 return result; 3119 } 3120 3121 /** 3122 * Returns a formatted string using the specified format string and 3123 * arguments. 3124 * 3125 * <p> The locale always used is the one returned by {@link 3126 * java.util.Locale#getDefault() Locale.getDefault()}. 3127 * 3128 * @param format 3129 * A <a href="../util/Formatter.html#syntax">format string</a> 3130 * 3131 * @param args 3132 * Arguments referenced by the format specifiers in the format 3133 * string. If there are more arguments than format specifiers, the 3134 * extra arguments are ignored. The number of arguments is 3135 * variable and may be zero. The maximum number of arguments is 3136 * limited by the maximum dimension of a Java array as defined by 3137 * <cite>The Java™ Virtual Machine Specification</cite>. 3138 * The behaviour on a 3139 * {@code null} argument depends on the <a 3140 * href="../util/Formatter.html#syntax">conversion</a>. 3141 * 3142 * @throws java.util.IllegalFormatException 3143 * If a format string contains an illegal syntax, a format 3144 * specifier that is incompatible with the given arguments, 3145 * insufficient arguments given the format string, or other 3146 * illegal conditions. For specification of all possible 3147 * formatting errors, see the <a 3148 * href="../util/Formatter.html#detail">Details</a> section of the 3149 * formatter class specification. 3150 * 3151 * @return A formatted string 3152 * 3153 * @see java.util.Formatter 3154 * @since 1.5 3155 */ 3156 public static String format(String format, Object... args) { 3157 return new Formatter().format(format, args).toString(); 3158 } 3159 3160 /** 3161 * Returns a formatted string using the specified locale, format string, 3162 * and arguments. 3163 * 3164 * @param l 3165 * The {@linkplain java.util.Locale locale} to apply during 3166 * formatting. If {@code l} is {@code null} then no localization 3167 * is applied. 3168 * 3169 * @param format 3170 * A <a href="../util/Formatter.html#syntax">format string</a> 3171 * 3172 * @param args 3173 * Arguments referenced by the format specifiers in the format 3174 * string. If there are more arguments than format specifiers, the 3175 * extra arguments are ignored. The number of arguments is 3176 * variable and may be zero. The maximum number of arguments is 3177 * limited by the maximum dimension of a Java array as defined by 3178 * <cite>The Java™ Virtual Machine Specification</cite>. 3179 * The behaviour on a 3180 * {@code null} argument depends on the 3181 * <a href="../util/Formatter.html#syntax">conversion</a>. 3182 * 3183 * @throws java.util.IllegalFormatException 3184 * If a format string contains an illegal syntax, a format 3185 * specifier that is incompatible with the given arguments, 3186 * insufficient arguments given the format string, or other 3187 * illegal conditions. For specification of all possible 3188 * formatting errors, see the <a 3189 * href="../util/Formatter.html#detail">Details</a> section of the 3190 * formatter class specification 3191 * 3192 * @return A formatted string 3193 * 3194 * @see java.util.Formatter 3195 * @since 1.5 3196 */ 3197 public static String format(Locale l, String format, Object... args) { 3198 return new Formatter(l).format(format, args).toString(); 3199 } 3200 3201 /** 3202 * Returns the string representation of the {@code Object} argument. 3203 * 3204 * @param obj an {@code Object}. 3205 * @return if the argument is {@code null}, then a string equal to 3206 * {@code "null"}; otherwise, the value of 3207 * {@code obj.toString()} is returned. 3208 * @see java.lang.Object#toString() 3209 */ 3210 public static String valueOf(Object obj) { 3211 return (obj == null) ? "null" : obj.toString(); 3212 } 3213 3214 /** 3215 * Returns the string representation of the {@code char} array 3216 * argument. The contents of the character array are copied; subsequent 3217 * modification of the character array does not affect the returned 3218 * string. 3219 * 3220 * @param data the character array. 3221 * @return a {@code String} that contains the characters of the 3222 * character array. 3223 */ 3224 public static String valueOf(char data[]) { 3225 return new String(data); 3226 } 3227 3228 /** 3229 * Returns the string representation of a specific subarray of the 3230 * {@code char} array argument. 3231 * <p> 3232 * The {@code offset} argument is the index of the first 3233 * character of the subarray. The {@code count} argument 3234 * specifies the length of the subarray. The contents of the subarray 3235 * are copied; subsequent modification of the character array does not 3236 * affect the returned string. 3237 * 3238 * @param data the character array. 3239 * @param offset initial offset of the subarray. 3240 * @param count length of the subarray. 3241 * @return a {@code String} that contains the characters of the 3242 * specified subarray of the character array. 3243 * @exception IndexOutOfBoundsException if {@code offset} is 3244 * negative, or {@code count} is negative, or 3245 * {@code offset+count} is larger than 3246 * {@code data.length}. 3247 */ 3248 public static String valueOf(char data[], int offset, int count) { 3249 return new String(data, offset, count); 3250 } 3251 3252 /** 3253 * Equivalent to {@link #valueOf(char[], int, int)}. 3254 * 3255 * @param data the character array. 3256 * @param offset initial offset of the subarray. 3257 * @param count length of the subarray. 3258 * @return a {@code String} that contains the characters of the 3259 * specified subarray of the character array. 3260 * @exception IndexOutOfBoundsException if {@code offset} is 3261 * negative, or {@code count} is negative, or 3262 * {@code offset+count} is larger than 3263 * {@code data.length}. 3264 */ 3265 public static String copyValueOf(char data[], int offset, int count) { 3266 return new String(data, offset, count); 3267 } 3268 3269 /** 3270 * Equivalent to {@link #valueOf(char[])}. 3271 * 3272 * @param data the character array. 3273 * @return a {@code String} that contains the characters of the 3274 * character array. 3275 */ 3276 public static String copyValueOf(char data[]) { 3277 return new String(data); 3278 } 3279 3280 /** 3281 * Returns the string representation of the {@code boolean} argument. 3282 * 3283 * @param b a {@code boolean}. 3284 * @return if the argument is {@code true}, a string equal to 3285 * {@code "true"} is returned; otherwise, a string equal to 3286 * {@code "false"} is returned. 3287 */ 3288 public static String valueOf(boolean b) { 3289 return b ? "true" : "false"; 3290 } 3291 3292 /** 3293 * Returns the string representation of the {@code char} 3294 * argument. 3295 * 3296 * @param c a {@code char}. 3297 * @return a string of length {@code 1} containing 3298 * as its single character the argument {@code c}. 3299 */ 3300 public static String valueOf(char c) { 3301 return new String(new char[]{c}, true); 3302 } 3303 3304 /** 3305 * Returns the string representation of the {@code int} argument. 3306 * <p> 3307 * The representation is exactly the one returned by the 3308 * {@code Integer.toString} method of one argument. 3309 * 3310 * @param i an {@code int}. 3311 * @return a string representation of the {@code int} argument. 3312 * @see java.lang.Integer#toString(int, int) 3313 */ 3314 public static String valueOf(int i) { 3315 return Integer.toString(i); 3316 } 3317 3318 /** 3319 * Returns the string representation of the {@code long} argument. 3320 * <p> 3321 * The representation is exactly the one returned by the 3322 * {@code Long.toString} method of one argument. 3323 * 3324 * @param l a {@code long}. 3325 * @return a string representation of the {@code long} argument. 3326 * @see java.lang.Long#toString(long) 3327 */ 3328 public static String valueOf(long l) { 3329 return Long.toString(l); 3330 } 3331 3332 /** 3333 * Returns the string representation of the {@code float} argument. 3334 * <p> 3335 * The representation is exactly the one returned by the 3336 * {@code Float.toString} method of one argument. 3337 * 3338 * @param f a {@code float}. 3339 * @return a string representation of the {@code float} argument. 3340 * @see java.lang.Float#toString(float) 3341 */ 3342 public static String valueOf(float f) { 3343 return Float.toString(f); 3344 } 3345 3346 /** 3347 * Returns the string representation of the {@code double} argument. 3348 * <p> 3349 * The representation is exactly the one returned by the 3350 * {@code Double.toString} method of one argument. 3351 * 3352 * @param d a {@code double}. 3353 * @return a string representation of the {@code double} argument. 3354 * @see java.lang.Double#toString(double) 3355 */ 3356 public static String valueOf(double d) { 3357 return Double.toString(d); 3358 } 3359 3360 /** 3361 * Returns a canonical representation for the string object. 3362 * <p> 3363 * A pool of strings, initially empty, is maintained privately by the 3364 * class {@code String}. 3365 * <p> 3366 * When the intern method is invoked, if the pool already contains a 3367 * string equal to this {@code String} object as determined by 3368 * the {@link #equals(Object)} method, then the string from the pool is 3369 * returned. Otherwise, this {@code String} object is added to the 3370 * pool and a reference to this {@code String} object is returned. 3371 * <p> 3372 * It follows that for any two strings {@code s} and {@code t}, 3373 * {@code s.intern() == t.intern()} is {@code true} 3374 * if and only if {@code s.equals(t)} is {@code true}. 3375 * <p> 3376 * All literal strings and string-valued constant expressions are 3377 * interned. String literals are defined in section 3.10.5 of the 3378 * <cite>The Java™ Language Specification</cite>. 3379 * 3380 * @return a string that has the same contents as this string, but is 3381 * guaranteed to be from a pool of unique strings. 3382 */ 3383 public native String intern(); 3384 }