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