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| 1 | /* | ||
| 2 | * Copyright (c) 1994, 2006, 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 | /** | ||
| 29 | * The Boolean class wraps a value of the primitive type | ||
| 30 | * {@code boolean} in an object. An object of type | ||
| 31 | * {@code Boolean} contains a single field whose type is | ||
| 32 | * {@code boolean}. | ||
| 33 | * <p> | ||
| 34 | * In addition, this class provides many methods for | ||
| 35 | * converting a {@code boolean} to a {@code String} and a | ||
| 36 | * {@code String} to a {@code boolean}, as well as other | ||
| 37 | * constants and methods useful when dealing with a | ||
| 38 | * {@code boolean}. | ||
| 39 | * | ||
| 40 | * @author Arthur van Hoff | ||
| 41 | * @since JDK1.0 | ||
| 42 | */ | ||
| 43 | public final class Boolean implements java.io.Serializable, | ||
| 44 | Comparable<Boolean> | ||
| 45 | { | ||
| 46 | /** | ||
| 47 | * The {@code Boolean} object corresponding to the primitive | ||
| 48 | * value {@code true}. | ||
| 49 | */ | ||
| 50 | public static final Boolean TRUE = new Boolean(true); | ||
| 51 | |||
| 52 | /** | ||
| 53 | * The {@code Boolean} object corresponding to the primitive | ||
| 54 | * value {@code false}. | ||
| 55 | */ | ||
| 56 | public static final Boolean FALSE = new Boolean(false); | ||
| 57 | |||
| 58 | /** | ||
| 59 | * The Class object representing the primitive type boolean. | ||
| 60 | * | ||
| 61 | * @since JDK1.1 | ||
| 62 | */ | ||
| 63 | public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean"); | ||
| 64 | |||
| 65 | /** | ||
| 66 | * The value of the Boolean. | ||
| 67 | * | ||
| 68 | * @serial | ||
| 69 | */ | ||
| 70 | private final boolean value; | ||
| 71 | |||
| 72 | /** use serialVersionUID from JDK 1.0.2 for interoperability */ | ||
| 73 | private static final long serialVersionUID = -3665804199014368530L; | ||
| 74 | |||
| 75 | /** | ||
| 76 | * Allocates a {@code Boolean} object representing the | ||
| 77 | * {@code value} argument. | ||
| 78 | * | ||
| 79 | * <p><b>Note: It is rarely appropriate to use this constructor. | ||
| 80 | * Unless a <i>new</i> instance is required, the static factory | ||
| 81 | * {@link #valueOf(boolean)} is generally a better choice. It is | ||
| 82 | * likely to yield significantly better space and time performance.</b> | ||
| 83 | * | ||
| 84 | * @param value the value of the {@code Boolean}. | ||
| 85 | */ | ||
| 86 | public Boolean(boolean value) { | ||
| 87 | this.value = value; | ||
| 88 | } | ||
| 89 | |||
| 90 | /** | ||
| 91 | * Allocates a {@code Boolean} object representing the value | ||
| 92 | * {@code true} if the string argument is not {@code null} | ||
| 93 | * and is equal, ignoring case, to the string {@code "true"}. | ||
| 94 | * Otherwise, allocate a {@code Boolean} object representing the | ||
| 95 | * value {@code false}. Examples:<p> | ||
| 96 | * {@code new Boolean("True")} produces a {@code Boolean} object | ||
| 97 | * that represents {@code true}.<br> | ||
| 98 | * {@code new Boolean("yes")} produces a {@code Boolean} object | ||
| 99 | * that represents {@code false}. | ||
| 100 | * | ||
| 101 | * @param s the string to be converted to a {@code Boolean}. | ||
| 102 | */ | ||
| 103 | public Boolean(String s) { | ||
| 104 | this(toBoolean(s)); | ||
| 105 | } | ||
| 106 | |||
| 107 | /** | ||
| 108 | * Parses the string argument as a boolean. The {@code boolean} | ||
| 109 | * returned represents the value {@code true} if the string argument | ||
| 110 | * is not {@code null} and is equal, ignoring case, to the string | ||
| 111 | * {@code "true"}. <p> | ||
| 112 | * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br> | ||
| 113 | * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}. | ||
| 114 | * | ||
| 115 | * @param s the {@code String} containing the boolean | ||
| 116 | * representation to be parsed | ||
| 117 | * @return the boolean represented by the string argument | ||
| 118 | * @since 1.5 | ||
| 119 | */ | ||
| 120 | public static boolean parseBoolean(String s) { | ||
| 121 | return toBoolean(s); | ||
| 122 | } | ||
| 123 | |||
| 124 | /** | ||
| 125 | * Returns the value of this {@code Boolean} object as a boolean | ||
| 126 | * primitive. | ||
| 127 | * | ||
| 128 | * @return the primitive {@code boolean} value of this object. | ||
| 129 | */ | ||
| 130 | public boolean booleanValue() { | ||
| 131 | return value; | ||
| 132 | } | ||
| 133 | |||
| 134 | /** | ||
| 135 | * Returns a {@code Boolean} instance representing the specified | ||
| 136 | * {@code boolean} value. If the specified {@code boolean} value | ||
| 137 | * is {@code true}, this method returns {@code Boolean.TRUE}; | ||
| 138 | * if it is {@code false}, this method returns {@code Boolean.FALSE}. | ||
| 139 | * If a new {@code Boolean} instance is not required, this method | ||
| 140 | * should generally be used in preference to the constructor | ||
| 141 | * {@link #Boolean(boolean)}, as this method is likely to yield | ||
| 142 | * significantly better space and time performance. | ||
| 143 | * | ||
| 144 | * @param b a boolean value. | ||
| 145 | * @return a {@code Boolean} instance representing {@code b}. | ||
| 146 | * @since 1.4 | ||
| 147 | */ | ||
| 148 | public static Boolean valueOf(boolean b) { | ||
| 149 | return (b ? TRUE : FALSE); | ||
| 150 | } | ||
| 151 | |||
| 152 | /** | ||
| 153 | * Returns a {@code Boolean} with a value represented by the | ||
| 154 | * specified string. The {@code Boolean} returned represents a | ||
| 155 | * true value if the string argument is not {@code null} | ||
| 156 | * and is equal, ignoring case, to the string {@code "true"}. | ||
| 157 | * | ||
| 158 | * @param s a string. | ||
| 159 | * @return the {@code Boolean} value represented by the string. | ||
| 160 | */ | ||
| 161 | public static Boolean valueOf(String s) { | ||
| 162 | return toBoolean(s) ? TRUE : FALSE; | ||
| 163 | } | ||
| 164 | |||
| 165 | /** | ||
| 166 | * Returns a {@code String} object representing the specified | ||
| 167 | * boolean. If the specified boolean is {@code true}, then | ||
| 168 | * the string {@code "true"} will be returned, otherwise the | ||
| 169 | * string {@code "false"} will be returned. | ||
| 170 | * | ||
| 171 | * @param b the boolean to be converted | ||
| 172 | * @return the string representation of the specified {@code boolean} | ||
| 173 | * @since 1.4 | ||
| 174 | */ | ||
| 175 | public static String toString(boolean b) { | ||
| 176 | return b ? "true" : "false"; | ||
| 177 | } | ||
| 178 | |||
| 179 | /** | ||
| 180 | * Returns a {@code String} object representing this Boolean's | ||
| 181 | * value. If this object represents the value {@code true}, | ||
| 182 | * a string equal to {@code "true"} is returned. Otherwise, a | ||
| 183 | * string equal to {@code "false"} is returned. | ||
| 184 | * | ||
| 185 | * @return a string representation of this object. | ||
| 186 | */ | ||
| 187 | public String toString() { | ||
| 188 | return value ? "true" : "false"; | ||
| 189 | } | ||
| 190 | |||
| 191 | /** | ||
| 192 | * Returns a hash code for this {@code Boolean} object. | ||
| 193 | * | ||
| 194 | * @return the integer {@code 1231} if this object represents | ||
| 195 | * {@code true}; returns the integer {@code 1237} if this | ||
| 196 | * object represents {@code false}. | ||
| 197 | */ | ||
| 198 | public int hashCode() { | ||
| 199 | return value ? 1231 : 1237; | ||
| 200 | } | ||
| 201 | |||
| 202 | /** | ||
| 203 | * Returns {@code true} if and only if the argument is not | ||
| 204 | * {@code null} and is a {@code Boolean} object that | ||
| 205 | * represents the same {@code boolean} value as this object. | ||
| 206 | * | ||
| 207 | * @param obj the object to compare with. | ||
| 208 | * @return {@code true} if the Boolean objects represent the | ||
| 209 | * same value; {@code false} otherwise. | ||
| 210 | */ | ||
| 211 | public boolean equals(Object obj) { | ||
| 212 | if (obj instanceof Boolean) { | ||
| 213 | return value == ((Boolean)obj).booleanValue(); | ||
| 214 | } | ||
| 215 | return false; | ||
| 216 | } | ||
| 217 | |||
| 218 | /** | ||
| 219 | * Returns {@code true} if and only if the system property | ||
| 220 | * named by the argument exists and is equal to the string | ||
| 221 | * {@code "true"}. (Beginning with version 1.0.2 of the | ||
| 222 | * Java<small><sup>TM</sup></small> platform, the test of | ||
| 223 | * this string is case insensitive.) A system property is accessible | ||
| 224 | * through {@code getProperty}, a method defined by the | ||
| 225 | * {@code System} class. | ||
| 226 | * <p> | ||
| 227 | * If there is no property with the specified name, or if the specified | ||
| 228 | * name is empty or null, then {@code false} is returned. | ||
| 229 | * | ||
| 230 | * @param name the system property name. | ||
| 231 | * @return the {@code boolean} value of the system property. | ||
| 232 | * @see java.lang.System#getProperty(java.lang.String) | ||
| 233 | * @see java.lang.System#getProperty(java.lang.String, java.lang.String) | ||
| 234 | */ | ||
| 235 | public static boolean getBoolean(String name) { | ||
| 236 | boolean result = false; | ||
| 237 | try { | ||
| 238 | result = toBoolean(System.getProperty(name)); | ||
| 239 | } catch (IllegalArgumentException e) { | ||
| 240 | } catch (NullPointerException e) { | ||
| 241 | } | ||
| 242 | return result; | ||
| 243 | } | ||
| 244 | |||
| 245 | /** | ||
| 246 | * Compares this {@code Boolean} instance with another. | ||
| 247 | * | ||
| 248 | * @param b the {@code Boolean} instance to be compared | ||
| 249 | * @return zero if this object represents the same boolean value as the | ||
| 250 | * argument; a positive value if this object represents true | ||
| 251 | * and the argument represents false; and a negative value if | ||
| 252 | * this object represents false and the argument represents true | ||
| 253 | * @throws NullPointerException if the argument is {@code null} | ||
| 254 | * @see Comparable | ||
| 255 | * @since 1.5 | ||
| 256 | */ | ||
| 257 | public int compareTo(Boolean b) { | ||
| 258 | return compare(this.value, b.value); | ||
| 259 | } | ||
| 260 | |||
| 261 | /** | ||
| 262 | * Compares two {@code boolean} values. | ||
| 263 | * The value returned is identical to what would be returned by: | ||
| 264 | * <pre> | ||
| 265 | * Boolean.valueOf(x).compareTo(Boolean.valueOf(y)) | ||
| 266 | * </pre> | ||
| 267 | * | ||
| 268 | * @param x the first {@code boolean} to compare | ||
| 269 | * @param y the second {@code boolean} to compare | ||
| 270 | * @return the value {@code 0} if {@code x == y}; | ||
| 271 | * a value less than {@code 0} if {@code !x && y}; and | ||
| 272 | * a value greater than {@code 0} if {@code x && !y} | ||
| 273 | * @since 1.7 | ||
| 274 | */ | ||
| 275 | public static int compare(boolean x, boolean y) { | ||
| 276 | return (x == y) ? 0 : (x ? 1 : -1); | ||
| 277 | } | ||
| 278 | |||
| 279 | private static boolean toBoolean(String name) { | ||
| 280 | return ((name != null) && name.equalsIgnoreCase("true")); | ||
| 281 | } | ||
| 282 | } | ||