1 /* 2 * Copyright (c) 2003, 2008, 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 29 /** 30 * A mutable sequence of characters. This class provides an API compatible 31 * with <code>StringBuffer</code>, but with no guarantee of synchronization. 32 * This class is designed for use as a drop-in replacement for 33 * <code>StringBuffer</code> in places where the string buffer was being 34 * used by a single thread (as is generally the case). Where possible, 35 * it is recommended that this class be used in preference to 36 * <code>StringBuffer</code> as it will be faster under most implementations. 37 * 38 * <p>The principal operations on a <code>StringBuilder</code> are the 39 * <code>append</code> and <code>insert</code> methods, which are 40 * overloaded so as to accept data of any type. Each effectively 41 * converts a given datum to a string and then appends or inserts the 42 * characters of that string to the string builder. The 43 * <code>append</code> method always adds these characters at the end 44 * of the builder; the <code>insert</code> method adds the characters at 45 * a specified point. 46 * <p> 47 * For example, if <code>z</code> refers to a string builder object 48 * whose current contents are "<code>start</code>", then 49 * the method call <code>z.append("le")</code> would cause the string 50 * builder to contain "<code>startle</code>", whereas 51 * <code>z.insert(4, "le")</code> would alter the string builder to 52 * contain "<code>starlet</code>". 53 * <p> 54 * In general, if sb refers to an instance of a <code>StringBuilder</code>, 55 * then <code>sb.append(x)</code> has the same effect as 56 * <code>sb.insert(sb.length(), x)</code>. 57 * 58 * Every string builder has a capacity. As long as the length of the 59 * character sequence contained in the string builder does not exceed 60 * the capacity, it is not necessary to allocate a new internal 61 * buffer. If the internal buffer overflows, it is automatically made larger. 62 * 63 * <p>Instances of <code>StringBuilder</code> are not safe for 64 * use by multiple threads. If such synchronization is required then it is 65 * recommended that {@link java.lang.StringBuffer} be used. 66 * 67 * @author Michael McCloskey 68 * @see java.lang.StringBuffer 69 * @see java.lang.String 70 * @since 1.5 71 */ 72 public final class StringBuilder 73 extends AbstractStringBuilder 74 implements java.io.Serializable, CharSequence 75 { 76 77 /** use serialVersionUID for interoperability */ 78 static final long serialVersionUID = 4383685877147921099L; 79 80 /** 81 * Constructs a string builder with no characters in it and an 82 * initial capacity of 16 characters. 83 */ 84 public StringBuilder() { 85 super(16); 86 } 87 88 /** 89 * Constructs a string builder with no characters in it and an 90 * initial capacity specified by the <code>capacity</code> argument. 91 * 92 * @param capacity the initial capacity. 93 * @throws NegativeArraySizeException if the <code>capacity</code> 94 * argument is less than <code>0</code>. 95 */ 96 public StringBuilder(int capacity) { 97 super(capacity); 98 } 99 100 /** 101 * Constructs a string builder initialized to the contents of the 102 * specified string. The initial capacity of the string builder is 103 * <code>16</code> plus the length of the string argument. 104 * 105 * @param str the initial contents of the buffer. 106 * @throws NullPointerException if <code>str</code> is <code>null</code> 107 */ 108 public StringBuilder(String str) { 109 super(str.length() + 16); 110 append(str); 111 } 112 113 /** 114 * Constructs a string builder that contains the same characters 115 * as the specified <code>CharSequence</code>. The initial capacity of 116 * the string builder is <code>16</code> plus the length of the 117 * <code>CharSequence</code> argument. 118 * 119 * @param seq the sequence to copy. 120 * @throws NullPointerException if <code>seq</code> is <code>null</code> 121 */ 122 public StringBuilder(CharSequence seq) { 123 this(seq.length() + 16); 124 append(seq); 125 } 126 127 public StringBuilder append(Object obj) { 128 return append(String.valueOf(obj)); 129 } 130 131 public StringBuilder append(String str) { 132 super.append(str); 133 return this; 134 } 135 136 // Appends the specified string builder to this sequence. 137 private StringBuilder append(StringBuilder sb) { 138 if (sb == null) 139 return append("null"); 140 int len = sb.length(); 141 int newcount = count + len; 142 if (newcount > value.length) 143 expandCapacity(newcount); 144 sb.getChars(0, len, value, count); 145 count = newcount; 146 return this; 147 } 148 149 /** 150 * Appends the specified <tt>StringBuffer</tt> to this sequence. 151 * <p> 152 * The characters of the <tt>StringBuffer</tt> argument are appended, 153 * in order, to this sequence, increasing the 154 * length of this sequence by the length of the argument. 155 * If <tt>sb</tt> is <tt>null</tt>, then the four characters 156 * <tt>"null"</tt> are appended to this sequence. 157 * <p> 158 * Let <i>n</i> be the length of this character sequence just prior to 159 * execution of the <tt>append</tt> method. Then the character at index 160 * <i>k</i> in the new character sequence is equal to the character at 161 * index <i>k</i> in the old character sequence, if <i>k</i> is less than 162 * <i>n</i>; otherwise, it is equal to the character at index <i>k-n</i> 163 * in the argument <code>sb</code>. 164 * 165 * @param sb the <tt>StringBuffer</tt> to append. 166 * @return a reference to this object. 167 */ 168 public StringBuilder append(StringBuffer sb) { 169 super.append(sb); 170 return this; 171 } 172 173 /** 174 */ 175 public StringBuilder append(CharSequence s) { 176 if (s == null) 177 s = "null"; 178 if (s instanceof String) 179 return this.append((String)s); 180 if (s instanceof StringBuffer) 181 return this.append((StringBuffer)s); 182 if (s instanceof StringBuilder) 183 return this.append((StringBuilder)s); 184 return this.append(s, 0, s.length()); 185 } 186 187 /** 188 * @throws IndexOutOfBoundsException {@inheritDoc} 189 */ 190 public StringBuilder append(CharSequence s, int start, int end) { 191 super.append(s, start, end); 192 return this; 193 } 194 195 public StringBuilder append(char[] str) { 196 super.append(str); 197 return this; 198 } 199 200 /** 201 * @throws IndexOutOfBoundsException {@inheritDoc} 202 */ 203 public StringBuilder append(char[] str, int offset, int len) { 204 super.append(str, offset, len); 205 return this; 206 } 207 208 public StringBuilder append(boolean b) { 209 super.append(b); 210 return this; 211 } 212 213 public StringBuilder append(char c) { 214 super.append(c); 215 return this; 216 } 217 218 public StringBuilder append(int i) { 219 super.append(i); 220 return this; 221 } 222 223 public StringBuilder append(long lng) { 224 super.append(lng); 225 return this; 226 } 227 228 public StringBuilder append(float f) { 229 super.append(f); 230 return this; 231 } 232 233 public StringBuilder append(double d) { 234 super.append(d); 235 return this; 236 } 237 238 /** 239 * @since 1.5 240 */ 241 public StringBuilder appendCodePoint(int codePoint) { 242 super.appendCodePoint(codePoint); 243 return this; 244 } 245 246 /** 247 * @throws StringIndexOutOfBoundsException {@inheritDoc} 248 */ 249 public StringBuilder delete(int start, int end) { 250 super.delete(start, end); 251 return this; 252 } 253 254 /** 255 * @throws StringIndexOutOfBoundsException {@inheritDoc} 256 */ 257 public StringBuilder deleteCharAt(int index) { 258 super.deleteCharAt(index); 259 return this; 260 } 261 262 /** 263 * @throws StringIndexOutOfBoundsException {@inheritDoc} 264 */ 265 public StringBuilder replace(int start, int end, String str) { 266 super.replace(start, end, str); 267 return this; 268 } 269 270 /** 271 * @throws StringIndexOutOfBoundsException {@inheritDoc} 272 */ 273 public StringBuilder insert(int index, char[] str, int offset, 274 int len) 275 { 276 super.insert(index, str, offset, len); 277 return this; 278 } 279 280 /** 281 * @throws StringIndexOutOfBoundsException {@inheritDoc} 282 */ 283 public StringBuilder insert(int offset, Object obj) { 284 return insert(offset, String.valueOf(obj)); 285 } 286 287 /** 288 * @throws StringIndexOutOfBoundsException {@inheritDoc} 289 */ 290 public StringBuilder insert(int offset, String str) { 291 super.insert(offset, str); 292 return this; 293 } 294 295 /** 296 * @throws StringIndexOutOfBoundsException {@inheritDoc} 297 */ 298 public StringBuilder insert(int offset, char[] str) { 299 super.insert(offset, str); 300 return this; 301 } 302 303 /** 304 * @throws IndexOutOfBoundsException {@inheritDoc} 305 */ 306 public StringBuilder insert(int dstOffset, CharSequence s) { 307 if (s == null) 308 s = "null"; 309 if (s instanceof String) 310 return this.insert(dstOffset, (String)s); 311 return this.insert(dstOffset, s, 0, s.length()); 312 } 313 314 /** 315 * @throws IndexOutOfBoundsException {@inheritDoc} 316 */ 317 public StringBuilder insert(int dstOffset, CharSequence s, 318 int start, int end) 319 { 320 super.insert(dstOffset, s, start, end); 321 return this; 322 } 323 324 /** 325 * @throws StringIndexOutOfBoundsException {@inheritDoc} 326 */ 327 public StringBuilder insert(int offset, boolean b) { 328 super.insert(offset, b); 329 return this; 330 } 331 332 /** 333 * @throws IndexOutOfBoundsException {@inheritDoc} 334 */ 335 public StringBuilder insert(int offset, char c) { 336 super.insert(offset, c); 337 return this; 338 } 339 340 /** 341 * @throws StringIndexOutOfBoundsException {@inheritDoc} 342 */ 343 public StringBuilder insert(int offset, int i) { 344 return insert(offset, String.valueOf(i)); 345 } 346 347 /** 348 * @throws StringIndexOutOfBoundsException {@inheritDoc} 349 */ 350 public StringBuilder insert(int offset, long l) { 351 return insert(offset, String.valueOf(l)); 352 } 353 354 /** 355 * @throws StringIndexOutOfBoundsException {@inheritDoc} 356 */ 357 public StringBuilder insert(int offset, float f) { 358 return insert(offset, String.valueOf(f)); 359 } 360 361 /** 362 * @throws StringIndexOutOfBoundsException {@inheritDoc} 363 */ 364 public StringBuilder insert(int offset, double d) { 365 return insert(offset, String.valueOf(d)); 366 } 367 368 /** 369 * @throws NullPointerException {@inheritDoc} 370 */ 371 public int indexOf(String str) { 372 return indexOf(str, 0); 373 } 374 375 /** 376 * @throws NullPointerException {@inheritDoc} 377 */ 378 public int indexOf(String str, int fromIndex) { 379 return String.indexOf(value, 0, count, 380 str.toCharArray(), 0, str.length(), fromIndex); 381 } 382 383 /** 384 * @throws NullPointerException {@inheritDoc} 385 */ 386 public int lastIndexOf(String str) { 387 return lastIndexOf(str, count); 388 } 389 390 /** 391 * @throws NullPointerException {@inheritDoc} 392 */ 393 public int lastIndexOf(String str, int fromIndex) { 394 return String.lastIndexOf(value, 0, count, 395 str.toCharArray(), 0, str.length(), fromIndex); 396 } 397 398 public StringBuilder reverse() { 399 super.reverse(); 400 return this; 401 } 402 403 public String toString() { 404 // Create a copy, don't share the array 405 return new String(value, 0, count); 406 } 407 408 /** 409 * Save the state of the <tt>StringBuilder</tt> instance to a stream 410 * (that is, serialize it). 411 * 412 * @serialData the number of characters currently stored in the string 413 * builder (<tt>int</tt>), followed by the characters in the 414 * string builder (<tt>char[]</tt>). The length of the 415 * <tt>char</tt> array may be greater than the number of 416 * characters currently stored in the string builder, in which 417 * case extra characters are ignored. 418 */ 419 private void writeObject(java.io.ObjectOutputStream s) 420 throws java.io.IOException { 421 s.defaultWriteObject(); 422 s.writeInt(count); 423 s.writeObject(value); 424 } 425 426 /** 427 * readObject is called to restore the state of the StringBuffer from 428 * a stream. 429 */ 430 private void readObject(java.io.ObjectInputStream s) 431 throws java.io.IOException, ClassNotFoundException { 432 s.defaultReadObject(); 433 count = s.readInt(); 434 value = (char[]) s.readObject(); 435 } 436 437 }