1 /* 2 * Copyright (c) 1994, 2021, 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.vm.annotation.IntrinsicCandidate; 29 30 import java.lang.constant.Constable; 31 import java.lang.constant.ConstantDesc; 32 import java.lang.constant.ConstantDescs; 33 import java.lang.constant.DynamicConstantDesc; 34 import java.util.Optional; 35 36 import static java.lang.constant.ConstantDescs.BSM_GET_STATIC_FINAL; 37 import static java.lang.constant.ConstantDescs.CD_Boolean; 38 39 /** 40 * The Boolean class wraps a value of the primitive type 41 * {@code boolean} in an object. An object of type 42 * {@code Boolean} contains a single field whose type is 43 * {@code boolean}. 44 * 45 * <p>In addition, this class provides many methods for 46 * converting a {@code boolean} to a {@code String} and a 47 * {@code String} to a {@code boolean}, as well as other 48 * constants and methods useful when dealing with a 49 * {@code boolean}. 50 * 51 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a> 52 * class; programmers should treat instances that are 53 * {@linkplain #equals(Object) equal} as interchangeable and should not 54 * use instances for synchronization, or unpredictable behavior may 55 * occur. For example, in a future release, synchronization may fail. 56 * 57 * @author Arthur van Hoff 58 * @since 1.0 59 */ 60 @jdk.internal.MigratedValueClass 61 @jdk.internal.ValueBased 62 public final class Boolean implements java.io.Serializable, 63 Comparable<Boolean>, Constable 64 { 65 /** 66 * The {@code Boolean} object corresponding to the primitive 67 * value {@code true}. 68 */ 69 public static final Boolean TRUE = new Boolean(true); 70 71 /** 72 * The {@code Boolean} object corresponding to the primitive 73 * value {@code false}. 74 */ 75 public static final Boolean FALSE = new Boolean(false); 76 77 /** 78 * The Class object representing the primitive type boolean. 79 * 80 * @since 1.1 81 */ 82 @SuppressWarnings("unchecked") 83 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean"); 84 85 /** 86 * The value of the Boolean. 87 * 88 * @serial 89 */ 90 private final boolean value; 91 92 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 93 @java.io.Serial 94 private static final long serialVersionUID = -3665804199014368530L; 95 96 /** 97 * Allocates a {@code Boolean} object representing the 98 * {@code value} argument. 99 * 100 * @param value the value of the {@code Boolean}. 101 * 102 * @deprecated 103 * It is rarely appropriate to use this constructor. The static factory 104 * {@link #valueOf(boolean)} is generally a better choice, as it is 105 * likely to yield significantly better space and time performance. 106 * Also consider using the final fields {@link #TRUE} and {@link #FALSE} 107 * if possible. 108 */ 109 @Deprecated(since="9", forRemoval = true) 110 public Boolean(boolean value) { 111 this.value = value; 112 } 113 114 /** 115 * Allocates a {@code Boolean} object representing the value 116 * {@code true} if the string argument is not {@code null} 117 * and is equal, ignoring case, to the string {@code "true"}. 118 * Otherwise, allocates a {@code Boolean} object representing the 119 * value {@code false}. 120 * 121 * @param s the string to be converted to a {@code Boolean}. 122 * 123 * @deprecated 124 * It is rarely appropriate to use this constructor. 125 * Use {@link #parseBoolean(String)} to convert a string to a 126 * {@code boolean} primitive, or use {@link #valueOf(String)} 127 * to convert a string to a {@code Boolean} object. 128 */ 129 @Deprecated(since="9", forRemoval = true) 130 public Boolean(String s) { 131 this(parseBoolean(s)); 132 } 133 134 /** 135 * Parses the string argument as a boolean. The {@code boolean} 136 * returned represents the value {@code true} if the string argument 137 * is not {@code null} and is equal, ignoring case, to the string 138 * {@code "true"}. 139 * Otherwise, a false value is returned, including for a null 140 * argument.<p> 141 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br> 142 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}. 143 * 144 * @param s the {@code String} containing the boolean 145 * representation to be parsed 146 * @return the boolean represented by the string argument 147 * @since 1.5 148 */ 149 public static boolean parseBoolean(String s) { 150 return "true".equalsIgnoreCase(s); 151 } 152 153 /** 154 * Returns the value of this {@code Boolean} object as a boolean 155 * primitive. 156 * 157 * @return the primitive {@code boolean} value of this object. 158 */ 159 @IntrinsicCandidate 160 public boolean booleanValue() { 161 return value; 162 } 163 164 /** 165 * Returns a {@code Boolean} instance representing the specified 166 * {@code boolean} value. If the specified {@code boolean} value 167 * is {@code true}, this method returns {@code Boolean.TRUE}; 168 * if it is {@code false}, this method returns {@code Boolean.FALSE}. 169 * If a new {@code Boolean} instance is not required, this method 170 * should generally be used in preference to the constructor 171 * {@link #Boolean(boolean)}, as this method is likely to yield 172 * significantly better space and time performance. 173 * 174 * @param b a boolean value. 175 * @return a {@code Boolean} instance representing {@code b}. 176 * @since 1.4 177 */ 178 @IntrinsicCandidate 179 public static Boolean valueOf(boolean b) { 180 return (b ? TRUE : FALSE); 181 } 182 183 /** 184 * Returns a {@code Boolean} with a value represented by the 185 * specified string. The {@code Boolean} returned represents a 186 * true value if the string argument is not {@code null} 187 * and is equal, ignoring case, to the string {@code "true"}. 188 * Otherwise, a false value is returned, including for a null 189 * argument. 190 * 191 * @param s a string. 192 * @return the {@code Boolean} value represented by the string. 193 */ 194 public static Boolean valueOf(String s) { 195 return parseBoolean(s) ? TRUE : FALSE; 196 } 197 198 /** 199 * Returns a {@code String} object representing the specified 200 * boolean. If the specified boolean is {@code true}, then 201 * the string {@code "true"} will be returned, otherwise the 202 * string {@code "false"} will be returned. 203 * 204 * @param b the boolean to be converted 205 * @return the string representation of the specified {@code boolean} 206 * @since 1.4 207 */ 208 public static String toString(boolean b) { 209 return String.valueOf(b); 210 } 211 212 /** 213 * Returns a {@code String} object representing this Boolean's 214 * value. If this object represents the value {@code true}, 215 * a string equal to {@code "true"} is returned. Otherwise, a 216 * string equal to {@code "false"} is returned. 217 * 218 * @return a string representation of this object. 219 */ 220 @Override 221 public String toString() { 222 return String.valueOf(value); 223 } 224 225 /** 226 * Returns a hash code for this {@code Boolean} object. 227 * 228 * @return the integer {@code 1231} if this object represents 229 * {@code true}; returns the integer {@code 1237} if this 230 * object represents {@code false}. 231 */ 232 @Override 233 public int hashCode() { 234 return Boolean.hashCode(value); 235 } 236 237 /** 238 * Returns a hash code for a {@code boolean} value; compatible with 239 * {@code Boolean.hashCode()}. 240 * 241 * @param value the value to hash 242 * @return a hash code value for a {@code boolean} value. 243 * @since 1.8 244 */ 245 public static int hashCode(boolean value) { 246 return value ? 1231 : 1237; 247 } 248 249 /** 250 * Returns {@code true} if and only if the argument is not 251 * {@code null} and is a {@code Boolean} object that 252 * represents the same {@code boolean} value as this object. 253 * 254 * @param obj the object to compare with. 255 * @return {@code true} if the Boolean objects represent the 256 * same value; {@code false} otherwise. 257 */ 258 public boolean equals(Object obj) { 259 if (obj instanceof Boolean) { 260 return value == ((Boolean)obj).booleanValue(); 261 } 262 return false; 263 } 264 265 /** 266 * Returns {@code true} if and only if the system property named 267 * by the argument exists and is equal to, ignoring case, the 268 * string {@code "true"}. 269 * A system property is accessible through {@code getProperty}, a 270 * method defined by the {@code System} class. <p> If there is no 271 * property with the specified name, or if the specified name is 272 * empty or null, then {@code false} is returned. 273 * 274 * @param name the system property name. 275 * @return the {@code boolean} value of the system property. 276 * @throws SecurityException for the same reasons as 277 * {@link System#getProperty(String) System.getProperty} 278 * @see java.lang.System#getProperty(java.lang.String) 279 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 280 */ 281 public static boolean getBoolean(String name) { 282 boolean result = false; 283 try { 284 result = parseBoolean(System.getProperty(name)); 285 } catch (IllegalArgumentException | NullPointerException e) { 286 } 287 return result; 288 } 289 290 /** 291 * Compares this {@code Boolean} instance with another. 292 * 293 * @param b the {@code Boolean} instance to be compared 294 * @return zero if this object represents the same boolean value as the 295 * argument; a positive value if this object represents true 296 * and the argument represents false; and a negative value if 297 * this object represents false and the argument represents true 298 * @throws NullPointerException if the argument is {@code null} 299 * @see Comparable 300 * @since 1.5 301 */ 302 public int compareTo(Boolean b) { 303 return compare(this.value, b.value); 304 } 305 306 /** 307 * Compares two {@code boolean} values. 308 * The value returned is identical to what would be returned by: 309 * <pre> 310 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y)) 311 * </pre> 312 * 313 * @param x the first {@code boolean} to compare 314 * @param y the second {@code boolean} to compare 315 * @return the value {@code 0} if {@code x == y}; 316 * a value less than {@code 0} if {@code !x && y}; and 317 * a value greater than {@code 0} if {@code x && !y} 318 * @since 1.7 319 */ 320 public static int compare(boolean x, boolean y) { 321 return (x == y) ? 0 : (x ? 1 : -1); 322 } 323 324 /** 325 * Returns the result of applying the logical AND operator to the 326 * specified {@code boolean} operands. 327 * 328 * @param a the first operand 329 * @param b the second operand 330 * @return the logical AND of {@code a} and {@code b} 331 * @see java.util.function.BinaryOperator 332 * @since 1.8 333 */ 334 public static boolean logicalAnd(boolean a, boolean b) { 335 return a && b; 336 } 337 338 /** 339 * Returns the result of applying the logical OR operator to the 340 * specified {@code boolean} operands. 341 * 342 * @param a the first operand 343 * @param b the second operand 344 * @return the logical OR of {@code a} and {@code b} 345 * @see java.util.function.BinaryOperator 346 * @since 1.8 347 */ 348 public static boolean logicalOr(boolean a, boolean b) { 349 return a || b; 350 } 351 352 /** 353 * Returns the result of applying the logical XOR operator to the 354 * specified {@code boolean} operands. 355 * 356 * @param a the first operand 357 * @param b the second operand 358 * @return the logical XOR of {@code a} and {@code b} 359 * @see java.util.function.BinaryOperator 360 * @since 1.8 361 */ 362 public static boolean logicalXor(boolean a, boolean b) { 363 return a ^ b; 364 } 365 366 /** 367 * Returns an {@link Optional} containing the nominal descriptor for this 368 * instance. 369 * 370 * @return an {@link Optional} describing the {@linkplain Boolean} instance 371 * @since 15 372 */ 373 @Override 374 public Optional<DynamicConstantDesc<Boolean>> describeConstable() { 375 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE); 376 } 377 }