1 /* 2 * Copyright (c) 1994, 2013, 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 jdk.internal.HotSpotIntrinsicCandidate; 29 30 /** 31 * The Boolean class wraps a value of the primitive type 32 * {@code boolean} in an object. An object of type 33 * {@code Boolean} contains a single field whose type is 34 * {@code boolean}. 35 * <p> 36 * In addition, this class provides many methods for 37 * converting a {@code boolean} to a {@code String} and a 38 * {@code String} to a {@code boolean}, as well as other 39 * constants and methods useful when dealing with a 40 * {@code boolean}. 41 * 42 * @author Arthur van Hoff 43 * @since 1.0 44 */ 45 public final class Boolean implements java.io.Serializable, 46 Comparable<Boolean> 47 { 48 /** 49 * The {@code Boolean} object corresponding to the primitive 50 * value {@code true}. 51 */ 52 public static final Boolean TRUE = new Boolean(true); 53 54 /** 55 * The {@code Boolean} object corresponding to the primitive 56 * value {@code false}. 57 */ 58 public static final Boolean FALSE = new Boolean(false); 59 60 /** 61 * The Class object representing the primitive type boolean. 62 * 63 * @since 1.1 64 */ 65 @SuppressWarnings("unchecked") 66 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean"); 67 68 /** 69 * The value of the Boolean. 70 * 71 * @serial 72 */ 73 private final boolean value; 74 75 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 76 private static final long serialVersionUID = -3665804199014368530L; 77 78 /** 79 * Allocates a {@code Boolean} object representing the 80 * {@code value} argument. 81 * 82 * <p><b>Note: It is rarely appropriate to use this constructor. 83 * Unless a <i>new</i> instance is required, the static factory 84 * {@link #valueOf(boolean)} is generally a better choice. It is 85 * likely to yield significantly better space and time performance.</b> 86 * 87 * @param value the value of the {@code Boolean}. 88 */ 89 public Boolean(boolean value) { 90 this.value = value; 91 } 92 93 /** 94 * Allocates a {@code Boolean} object representing the value 95 * {@code true} if the string argument is not {@code null} 96 * and is equal, ignoring case, to the string {@code "true"}. 97 * Otherwise, allocate a {@code Boolean} object representing the 98 * value {@code false}. Examples:<p> 99 * {@code new Boolean("True")} produces a {@code Boolean} object 100 * that represents {@code true}.<br> 101 * {@code new Boolean("yes")} produces a {@code Boolean} object 102 * that represents {@code false}. 103 * 104 * @param s the string to be converted to a {@code Boolean}. 105 */ 106 public Boolean(String s) { 107 this(parseBoolean(s)); 108 } 109 110 /** 111 * Parses the string argument as a boolean. The {@code boolean} 112 * returned represents the value {@code true} if the string argument 113 * is not {@code null} and is equal, ignoring case, to the string 114 * {@code "true"}. <p> 115 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br> 116 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}. 117 * 118 * @param s the {@code String} containing the boolean 119 * representation to be parsed 120 * @return the boolean represented by the string argument 121 * @since 1.5 122 */ 123 public static boolean parseBoolean(String s) { 124 return ((s != null) && s.equalsIgnoreCase("true")); 125 } 126 127 /** 128 * Returns the value of this {@code Boolean} object as a boolean 129 * primitive. 130 * 131 * @return the primitive {@code boolean} value of this object. 132 */ 133 @HotSpotIntrinsicCandidate 134 public boolean booleanValue() { 135 return value; 136 } 137 138 /** 139 * Returns a {@code Boolean} instance representing the specified 140 * {@code boolean} value. If the specified {@code boolean} value 141 * is {@code true}, this method returns {@code Boolean.TRUE}; 142 * if it is {@code false}, this method returns {@code Boolean.FALSE}. 143 * If a new {@code Boolean} instance is not required, this method 144 * should generally be used in preference to the constructor 145 * {@link #Boolean(boolean)}, as this method is likely to yield 146 * significantly better space and time performance. 147 * 148 * @param b a boolean value. 149 * @return a {@code Boolean} instance representing {@code b}. 150 * @since 1.4 151 */ 152 @HotSpotIntrinsicCandidate 153 public static Boolean valueOf(boolean b) { 154 return (b ? TRUE : FALSE); 155 } 156 157 /** 158 * Returns a {@code Boolean} with a value represented by the 159 * specified string. The {@code Boolean} returned represents a 160 * true value if the string argument is not {@code null} 161 * and is equal, ignoring case, to the string {@code "true"}. 162 * 163 * @param s a string. 164 * @return the {@code Boolean} value represented by the string. 165 */ 166 public static Boolean valueOf(String s) { 167 return parseBoolean(s) ? TRUE : FALSE; 168 } 169 170 /** 171 * Returns a {@code String} object representing the specified 172 * boolean. If the specified boolean is {@code true}, then 173 * the string {@code "true"} will be returned, otherwise the 174 * string {@code "false"} will be returned. 175 * 176 * @param b the boolean to be converted 177 * @return the string representation of the specified {@code boolean} 178 * @since 1.4 179 */ 180 public static String toString(boolean b) { 181 return b ? "true" : "false"; 182 } 183 184 /** 185 * Returns a {@code String} object representing this Boolean's 186 * value. If this object represents the value {@code true}, 187 * a string equal to {@code "true"} is returned. Otherwise, a 188 * string equal to {@code "false"} is returned. 189 * 190 * @return a string representation of this object. 191 */ 192 public String toString() { 193 return value ? "true" : "false"; 194 } 195 196 /** 197 * Returns a hash code for this {@code Boolean} object. 198 * 199 * @return the integer {@code 1231} if this object represents 200 * {@code true}; returns the integer {@code 1237} if this 201 * object represents {@code false}. 202 */ 203 @Override 204 public int hashCode() { 205 return Boolean.hashCode(value); 206 } 207 208 /** 209 * Returns a hash code for a {@code boolean} value; compatible with 210 * {@code Boolean.hashCode()}. 211 * 212 * @param value the value to hash 213 * @return a hash code value for a {@code boolean} value. 214 * @since 1.8 215 */ 216 public static int hashCode(boolean value) { 217 return value ? 1231 : 1237; 218 } 219 220 /** 221 * Returns {@code true} if and only if the argument is not 222 * {@code null} and is a {@code Boolean} object that 223 * represents the same {@code boolean} value as this object. 224 * 225 * @param obj the object to compare with. 226 * @return {@code true} if the Boolean objects represent the 227 * same value; {@code false} otherwise. 228 */ 229 public boolean equals(Object obj) { 230 if (obj instanceof Boolean) { 231 return value == ((Boolean)obj).booleanValue(); 232 } 233 return false; 234 } 235 236 /** 237 * Returns {@code true} if and only if the system property named 238 * by the argument exists and is equal to the string {@code 239 * "true"}. (Beginning with version 1.0.2 of the Java™ 240 * platform, the test of this string is case insensitive.) A 241 * system property is accessible through {@code getProperty}, a 242 * method defined by the {@code System} class. 243 * <p> 244 * If there is no property with the specified name, or if the specified 245 * name is empty or null, then {@code false} is returned. 246 * 247 * @param name the system property name. 248 * @return the {@code boolean} value of the system property. 249 * @throws SecurityException for the same reasons as 250 * {@link System#getProperty(String) System.getProperty} 251 * @see java.lang.System#getProperty(java.lang.String) 252 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 253 */ 254 public static boolean getBoolean(String name) { 255 boolean result = false; 256 try { 257 result = parseBoolean(System.getProperty(name)); 258 } catch (IllegalArgumentException | NullPointerException e) { 259 } 260 return result; 261 } 262 263 /** 264 * Compares this {@code Boolean} instance with another. 265 * 266 * @param b the {@code Boolean} instance to be compared 267 * @return zero if this object represents the same boolean value as the 268 * argument; a positive value if this object represents true 269 * and the argument represents false; and a negative value if 270 * this object represents false and the argument represents true 271 * @throws NullPointerException if the argument is {@code null} 272 * @see Comparable 273 * @since 1.5 274 */ 275 public int compareTo(Boolean b) { 276 return compare(this.value, b.value); 277 } 278 279 /** 280 * Compares two {@code boolean} values. 281 * The value returned is identical to what would be returned by: 282 * <pre> 283 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y)) 284 * </pre> 285 * 286 * @param x the first {@code boolean} to compare 287 * @param y the second {@code boolean} to compare 288 * @return the value {@code 0} if {@code x == y}; 289 * a value less than {@code 0} if {@code !x && y}; and 290 * a value greater than {@code 0} if {@code x && !y} 291 * @since 1.7 292 */ 293 public static int compare(boolean x, boolean y) { 294 return (x == y) ? 0 : (x ? 1 : -1); 295 } 296 297 /** 298 * Returns the result of applying the logical AND operator to the 299 * specified {@code boolean} operands. 300 * 301 * @param a the first operand 302 * @param b the second operand 303 * @return the logical AND of {@code a} and {@code b} 304 * @see java.util.function.BinaryOperator 305 * @since 1.8 306 */ 307 public static boolean logicalAnd(boolean a, boolean b) { 308 return a && b; 309 } 310 311 /** 312 * Returns the result of applying the logical OR operator to the 313 * specified {@code boolean} operands. 314 * 315 * @param a the first operand 316 * @param b the second operand 317 * @return the logical OR of {@code a} and {@code b} 318 * @see java.util.function.BinaryOperator 319 * @since 1.8 320 */ 321 public static boolean logicalOr(boolean a, boolean b) { 322 return a || b; 323 } 324 325 /** 326 * Returns the result of applying the logical XOR operator to the 327 * specified {@code boolean} operands. 328 * 329 * @param a the first operand 330 * @param b the second operand 331 * @return the logical XOR of {@code a} and {@code b} 332 * @see java.util.function.BinaryOperator 333 * @since 1.8 334 */ 335 public static boolean logicalXor(boolean a, boolean b) { 336 return a ^ b; 337 } 338 }