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"}. <p> 121 * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br> 122 * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}. 123 * 124 * @param s the {@code String} containing the boolean 125 * representation to be parsed 126 * @return the boolean represented by the string argument 127 * @since 1.5 128 */ 129 public static boolean parseBoolean(String s) { 130 return ((s != null) && s.equalsIgnoreCase("true")); 131 } 132 133 /** 134 * Returns the value of this {@code Boolean} object as a boolean 135 * primitive. 136 * 137 * @return the primitive {@code boolean} value of this object. 138 */ 139 @HotSpotIntrinsicCandidate 140 public boolean booleanValue() { 141 return value; 142 } 143 144 /** 145 * Returns a {@code Boolean} instance representing the specified 146 * {@code boolean} value. If the specified {@code boolean} value 147 * is {@code true}, this method returns {@code Boolean.TRUE}; 148 * if it is {@code false}, this method returns {@code Boolean.FALSE}. 149 * If a new {@code Boolean} instance is not required, this method 150 * should generally be used in preference to the constructor 151 * {@link #Boolean(boolean)}, as this method is likely to yield 152 * significantly better space and time performance. 153 * 154 * @param b a boolean value. 155 * @return a {@code Boolean} instance representing {@code b}. 156 * @since 1.4 157 */ 158 @HotSpotIntrinsicCandidate 159 public static Boolean valueOf(boolean b) { 160 return (b ? TRUE : FALSE); 161 } 162 163 /** 164 * Returns a {@code Boolean} with a value represented by the 165 * specified string. The {@code Boolean} returned represents a 166 * true value if the string argument is not {@code null} 167 * and is equal, ignoring case, to the string {@code "true"}. 168 * 169 * @param s a string. 170 * @return the {@code Boolean} value represented by the string. 171 */ 172 public static Boolean valueOf(String s) { 173 return parseBoolean(s) ? TRUE : FALSE; 174 } 175 176 /** 177 * Returns a {@code String} object representing the specified 178 * boolean. If the specified boolean is {@code true}, then 179 * the string {@code "true"} will be returned, otherwise the 180 * string {@code "false"} will be returned. 181 * 182 * @param b the boolean to be converted 183 * @return the string representation of the specified {@code boolean} 184 * @since 1.4 185 */ 186 public static String toString(boolean b) { 187 return b ? "true" : "false"; 188 } 189 190 /** 191 * Returns a {@code String} object representing this Boolean's 192 * value. If this object represents the value {@code true}, 193 * a string equal to {@code "true"} is returned. Otherwise, a 194 * string equal to {@code "false"} is returned. 195 * 196 * @return a string representation of this object. 197 */ 198 public String toString() { 199 return value ? "true" : "false"; 200 } 201 202 /** 203 * Returns a hash code for this {@code Boolean} object. 204 * 205 * @return the integer {@code 1231} if this object represents 206 * {@code true}; returns the integer {@code 1237} if this 207 * object represents {@code false}. 208 */ 209 @Override 210 public int hashCode() { 211 return Boolean.hashCode(value); 212 } 213 214 /** 215 * Returns a hash code for a {@code boolean} value; compatible with 216 * {@code Boolean.hashCode()}. 217 * 218 * @param value the value to hash 219 * @return a hash code value for a {@code boolean} value. 220 * @since 1.8 221 */ 222 public static int hashCode(boolean value) { 223 return value ? 1231 : 1237; 224 } 225 226 /** 227 * Returns {@code true} if and only if the argument is not 228 * {@code null} and is a {@code Boolean} object that 229 * represents the same {@code boolean} value as this object. 230 * 231 * @param obj the object to compare with. 232 * @return {@code true} if the Boolean objects represent the 233 * same value; {@code false} otherwise. 234 */ 235 public boolean equals(Object obj) { 236 if (obj instanceof Boolean) { 237 return value == ((Boolean)obj).booleanValue(); 238 } 239 return false; 240 } 241 242 /** 243 * Returns {@code true} if and only if the system property named 244 * by the argument exists and is equal to the string {@code 245 * "true"}. (Beginning with version 1.0.2 of the Java™ 246 * platform, the test of this string is case insensitive.) A 247 * system property is accessible through {@code getProperty}, a 248 * method defined by the {@code System} class. 249 * <p> 250 * If there is no property with the specified name, or if the specified 251 * name is empty or null, then {@code false} is returned. 252 * 253 * @param name the system property name. 254 * @return the {@code boolean} value of the system property. 255 * @throws SecurityException for the same reasons as 256 * {@link System#getProperty(String) System.getProperty} 257 * @see java.lang.System#getProperty(java.lang.String) 258 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 259 */ 260 public static boolean getBoolean(String name) { 261 boolean result = false; 262 try { 263 result = parseBoolean(System.getProperty(name)); 264 } catch (IllegalArgumentException | NullPointerException e) { 265 } 266 return result; 267 } 268 269 /** 270 * Compares this {@code Boolean} instance with another. 271 * 272 * @param b the {@code Boolean} instance to be compared 273 * @return zero if this object represents the same boolean value as the 274 * argument; a positive value if this object represents true 275 * and the argument represents false; and a negative value if 276 * this object represents false and the argument represents true 277 * @throws NullPointerException if the argument is {@code null} 278 * @see Comparable 279 * @since 1.5 280 */ 281 public int compareTo(Boolean b) { 282 return compare(this.value, b.value); 283 } 284 285 /** 286 * Compares two {@code boolean} values. 287 * The value returned is identical to what would be returned by: 288 * <pre> 289 * Boolean.valueOf(x).compareTo(Boolean.valueOf(y)) 290 * </pre> 291 * 292 * @param x the first {@code boolean} to compare 293 * @param y the second {@code boolean} to compare 294 * @return the value {@code 0} if {@code x == y}; 295 * a value less than {@code 0} if {@code !x && y}; and 296 * a value greater than {@code 0} if {@code x && !y} 297 * @since 1.7 298 */ 299 public static int compare(boolean x, boolean y) { 300 return (x == y) ? 0 : (x ? 1 : -1); 301 } 302 303 /** 304 * Returns the result of applying the logical AND operator to the 305 * specified {@code boolean} operands. 306 * 307 * @param a the first operand 308 * @param b the second operand 309 * @return the logical AND of {@code a} and {@code b} 310 * @see java.util.function.BinaryOperator 311 * @since 1.8 312 */ 313 public static boolean logicalAnd(boolean a, boolean b) { 314 return a && b; 315 } 316 317 /** 318 * Returns the result of applying the logical OR operator to the 319 * specified {@code boolean} operands. 320 * 321 * @param a the first operand 322 * @param b the second operand 323 * @return the logical OR of {@code a} and {@code b} 324 * @see java.util.function.BinaryOperator 325 * @since 1.8 326 */ 327 public static boolean logicalOr(boolean a, boolean b) { 328 return a || b; 329 } 330 331 /** 332 * Returns the result of applying the logical XOR operator to the 333 * specified {@code boolean} operands. 334 * 335 * @param a the first operand 336 * @param b the second operand 337 * @return the logical XOR of {@code a} and {@code b} 338 * @see java.util.function.BinaryOperator 339 * @since 1.8 340 */ 341 public static boolean logicalXor(boolean a, boolean b) { 342 return a ^ b; 343 } 344 }