1 /* 2 * Copyright (c) 1994, 2020, 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.ValueBased 61 public final class Boolean implements java.io.Serializable, 62 Comparable<Boolean>, Constable 63 { 64 /** 65 * The {@code Boolean} object corresponding to the primitive 66 * value {@code true}. 67 */ 68 public static final Boolean TRUE = new Boolean(true); 69 70 /** 71 * The {@code Boolean} object corresponding to the primitive 72 * value {@code false}. 73 */ 74 public static final Boolean FALSE = new Boolean(false); 75 76 /** 77 * The Class object representing the primitive type boolean. 78 * 79 * @since 1.1 80 */ 81 @SuppressWarnings("unchecked") 82 public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean"); 83 84 /** 85 * The value of the Boolean. 86 * 87 * @serial 88 */ 89 private final boolean value; 90 91 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 92 @java.io.Serial 93 private static final long serialVersionUID = -3665804199014368530L; 94 95 /** 96 * Allocates a {@code Boolean} object representing the 97 * {@code value} argument. 98 * 99 * @param value the value of the {@code Boolean}. 100 * 101 * @deprecated 102 * It is rarely appropriate to use this constructor. The static factory 103 * {@link #valueOf(boolean)} is generally a better choice, as it is 104 * likely to yield significantly better space and time performance. 105 * Also consider using the final fields {@link #TRUE} and {@link #FALSE} 106 * if possible. 107 */ 108 @Deprecated(since="9", forRemoval = true) Boolean(boolean value)109 public Boolean(boolean value) { 110 this.value = value; 111 } 112 113 /** 114 * Allocates a {@code Boolean} object representing the value 115 * {@code true} if the string argument is not {@code null} 116 * and is equal, ignoring case, to the string {@code "true"}. 117 * Otherwise, allocates a {@code Boolean} object representing the 118 * value {@code false}. 119 * 120 * @param s the string to be converted to a {@code Boolean}. 121 * 122 * @deprecated 123 * It is rarely appropriate to use this constructor. 124 * Use {@link #parseBoolean(String)} to convert a string to a 125 * {@code boolean} primitive, or use {@link #valueOf(String)} 126 * to convert a string to a {@code Boolean} object. 127 */ 128 @Deprecated(since="9", forRemoval = true) Boolean(String s)129 public Boolean(String s) { 130 this(parseBoolean(s)); 131 } 132 133 /** 134 * Parses the string argument as a boolean. The {@code boolean} 135 * returned represents the value {@code true} if the string argument 136 * is not {@code null} and is equal, ignoring case, to the string 137 * {@code "true"}. 138 * Otherwise, a false value is returned, including for a null 139 * argument.<p> 140 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br> 141 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}. 142 * 143 * @param s the {@code String} containing the boolean 144 * representation to be parsed 145 * @return the boolean represented by the string argument 146 * @since 1.5 147 */ parseBoolean(String s)148 public static boolean parseBoolean(String s) { 149 return "true".equalsIgnoreCase(s); 150 } 151 152 /** 153 * Returns the value of this {@code Boolean} object as a boolean 154 * primitive. 155 * 156 * @return the primitive {@code boolean} value of this object. 157 */ 158 @IntrinsicCandidate booleanValue()159 public boolean booleanValue() { 160 return value; 161 } 162 163 /** 164 * Returns a {@code Boolean} instance representing the specified 165 * {@code boolean} value. If the specified {@code boolean} value 166 * is {@code true}, this method returns {@code Boolean.TRUE}; 167 * if it is {@code false}, this method returns {@code Boolean.FALSE}. 168 * If a new {@code Boolean} instance is not required, this method 169 * should generally be used in preference to the constructor 170 * {@link #Boolean(boolean)}, as this method is likely to yield 171 * significantly better space and time performance. 172 * 173 * @param b a boolean value. 174 * @return a {@code Boolean} instance representing {@code b}. 175 * @since 1.4 176 */ 177 @IntrinsicCandidate valueOf(boolean b)178 public static Boolean valueOf(boolean b) { 179 return (b ? TRUE : FALSE); 180 } 181 182 /** 183 * Returns a {@code Boolean} with a value represented by the 184 * specified string. The {@code Boolean} returned represents a 185 * true value if the string argument is not {@code null} 186 * and is equal, ignoring case, to the string {@code "true"}. 187 * Otherwise, a false value is returned, including for a null 188 * argument. 189 * 190 * @param s a string. 191 * @return the {@code Boolean} value represented by the string. 192 */ valueOf(String s)193 public static Boolean valueOf(String s) { 194 return parseBoolean(s) ? TRUE : FALSE; 195 } 196 197 /** 198 * Returns a {@code String} object representing the specified 199 * boolean. If the specified boolean is {@code true}, then 200 * the string {@code "true"} will be returned, otherwise the 201 * string {@code "false"} will be returned. 202 * 203 * @param b the boolean to be converted 204 * @return the string representation of the specified {@code boolean} 205 * @since 1.4 206 */ toString(boolean b)207 public static String toString(boolean b) { 208 return b ? "true" : "false"; 209 } 210 211 /** 212 * Returns a {@code String} object representing this Boolean's 213 * value. If this object represents the value {@code true}, 214 * a string equal to {@code "true"} is returned. Otherwise, a 215 * string equal to {@code "false"} is returned. 216 * 217 * @return a string representation of this object. 218 */ toString()219 public String toString() { 220 return value ? "true" : "false"; 221 } 222 223 /** 224 * Returns a hash code for this {@code Boolean} object. 225 * 226 * @return the integer {@code 1231} if this object represents 227 * {@code true}; returns the integer {@code 1237} if this 228 * object represents {@code false}. 229 */ 230 @Override hashCode()231 public int hashCode() { 232 return Boolean.hashCode(value); 233 } 234 235 /** 236 * Returns a hash code for a {@code boolean} value; compatible with 237 * {@code Boolean.hashCode()}. 238 * 239 * @param value the value to hash 240 * @return a hash code value for a {@code boolean} value. 241 * @since 1.8 242 */ hashCode(boolean value)243 public static int hashCode(boolean value) { 244 return value ? 1231 : 1237; 245 } 246 247 /** 248 * Returns {@code true} if and only if the argument is not 249 * {@code null} and is a {@code Boolean} object that 250 * represents the same {@code boolean} value as this object. 251 * 252 * @param obj the object to compare with. 253 * @return {@code true} if the Boolean objects represent the 254 * same value; {@code false} otherwise. 255 */ equals(Object obj)256 public boolean equals(Object obj) { 257 if (obj instanceof Boolean) { 258 return value == ((Boolean)obj).booleanValue(); 259 } 260 return false; 261 } 262 263 /** 264 * Returns {@code true} if and only if the system property named 265 * by the argument exists and is equal to, ignoring case, the 266 * string {@code "true"}. 267 * A system property is accessible through {@code getProperty}, a 268 * method defined by the {@code System} class. <p> If there is no 269 * property with the specified name, or if the specified name is 270 * empty or null, then {@code false} is returned. 271 * 272 * @param name the system property name. 273 * @return the {@code boolean} value of the system property. 274 * @throws SecurityException for the same reasons as 275 * {@link System#getProperty(String) System.getProperty} 276 * @see java.lang.System#getProperty(java.lang.String) 277 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 278 */ getBoolean(String name)279 public static boolean getBoolean(String name) { 280 boolean result = false; 281 try { 282 result = parseBoolean(System.getProperty(name)); 283 } catch (IllegalArgumentException | NullPointerException e) { 284 } 285 return result; 286 } 287 288 /** 289 * Compares this {@code Boolean} instance with another. 290 * 291 * @param b the {@code Boolean} instance to be compared 292 * @return zero if this object represents the same boolean value as the 293 * argument; a positive value if this object represents true 294 * and the argument represents false; and a negative value if 295 * this object represents false and the argument represents true 296 * @throws NullPointerException if the argument is {@code null} 297 * @see Comparable 298 * @since 1.5 299 */ compareTo(Boolean b)300 public int compareTo(Boolean b) { 301 return compare(this.value, b.value); 302 } 303 304 /** 305 * Compares two {@code boolean} values. 306 * The value returned is identical to what would be returned by: 307 * <pre> 308 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y)) 309 * </pre> 310 * 311 * @param x the first {@code boolean} to compare 312 * @param y the second {@code boolean} to compare 313 * @return the value {@code 0} if {@code x == y}; 314 * a value less than {@code 0} if {@code !x && y}; and 315 * a value greater than {@code 0} if {@code x && !y} 316 * @since 1.7 317 */ compare(boolean x, boolean y)318 public static int compare(boolean x, boolean y) { 319 return (x == y) ? 0 : (x ? 1 : -1); 320 } 321 322 /** 323 * Returns the result of applying the logical AND operator to the 324 * specified {@code boolean} operands. 325 * 326 * @param a the first operand 327 * @param b the second operand 328 * @return the logical AND of {@code a} and {@code b} 329 * @see java.util.function.BinaryOperator 330 * @since 1.8 331 */ logicalAnd(boolean a, boolean b)332 public static boolean logicalAnd(boolean a, boolean b) { 333 return a && b; 334 } 335 336 /** 337 * Returns the result of applying the logical OR operator to the 338 * specified {@code boolean} operands. 339 * 340 * @param a the first operand 341 * @param b the second operand 342 * @return the logical OR of {@code a} and {@code b} 343 * @see java.util.function.BinaryOperator 344 * @since 1.8 345 */ logicalOr(boolean a, boolean b)346 public static boolean logicalOr(boolean a, boolean b) { 347 return a || b; 348 } 349 350 /** 351 * Returns the result of applying the logical XOR operator to the 352 * specified {@code boolean} operands. 353 * 354 * @param a the first operand 355 * @param b the second operand 356 * @return the logical XOR of {@code a} and {@code b} 357 * @see java.util.function.BinaryOperator 358 * @since 1.8 359 */ logicalXor(boolean a, boolean b)360 public static boolean logicalXor(boolean a, boolean b) { 361 return a ^ b; 362 } 363 364 /** 365 * Returns an {@link Optional} containing the nominal descriptor for this 366 * instance. 367 * 368 * @return an {@link Optional} describing the {@linkplain Boolean} instance 369 * @since 15 370 */ 371 @Override describeConstable()372 public Optional<DynamicConstantDesc<Boolean>> describeConstable() { 373 return Optional.of(value ? ConstantDescs.TRUE : ConstantDescs.FALSE); 374 } 375 } 376