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      * <p><b>Note: It is rarely appropriate to use this constructor.
  83      * Unless a <i>new</i> instance is required, the static factory
  84      * {@link #valueOf(boolean)} is generally a better choice. It is
  85      * likely to yield significantly better space and time performance.</b>

  86      *
  87      * @param   value   the value of the {@code Boolean}.
  88      */

  89     public Boolean(boolean value) {
  90         this.value = value;
  91     }
  92 
  93     /**
  94      * Allocates a {@code Boolean} object representing the value
  95      * {@code true} if the string argument is not {@code null}
  96      * and is equal, ignoring case, to the string {@code "true"}.
  97      * Otherwise, allocate a {@code Boolean} object representing the
  98      * value {@code false}. Examples:<p>
  99      * {@code new Boolean("True")} produces a {@code Boolean} object
 100      * that represents {@code true}.<br>
 101      * {@code new Boolean("yes")} produces a {@code Boolean} object
 102      * that represents {@code false}.

 103      *
 104      * @param   s   the string to be converted to a {@code Boolean}.
 105      */

 106     public Boolean(String s) {
 107         this(parseBoolean(s));
 108     }
 109 
 110     /**
 111      * Parses the string argument as a boolean.  The {@code boolean}
 112      * returned represents the value {@code true} if the string argument
 113      * is not {@code null} and is equal, ignoring case, to the string
 114      * {@code "true"}. <p>
 115      * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
 116      * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
 117      *
 118      * @param      s   the {@code String} containing the boolean
 119      *                 representation to be parsed
 120      * @return     the boolean represented by the string argument
 121      * @since 1.5
 122      */
 123     public static boolean parseBoolean(String s) {
 124         return ((s != null) && s.equalsIgnoreCase("true"));
 125     }
 126 
 127     /**
 128      * Returns the value of this {@code Boolean} object as a boolean
 129      * primitive.
 130      *
 131      * @return  the primitive {@code boolean} value of this object.
 132      */
 133     @HotSpotIntrinsicCandidate
 134     public boolean booleanValue() {
 135         return value;
 136     }
 137 
 138     /**
 139      * Returns a {@code Boolean} instance representing the specified
 140      * {@code boolean} value.  If the specified {@code boolean} value
 141      * is {@code true}, this method returns {@code Boolean.TRUE};
 142      * if it is {@code false}, this method returns {@code Boolean.FALSE}.
 143      * If a new {@code Boolean} instance is not required, this method
 144      * should generally be used in preference to the constructor
 145      * {@link #Boolean(boolean)}, as this method is likely to yield
 146      * significantly better space and time performance.
 147      *
 148      * @param  b a boolean value.
 149      * @return a {@code Boolean} instance representing {@code b}.
 150      * @since  1.4
 151      */
 152     @HotSpotIntrinsicCandidate
 153     public static Boolean valueOf(boolean b) {
 154         return (b ? TRUE : FALSE);
 155     }
 156 
 157     /**
 158      * Returns a {@code Boolean} with a value represented by the
 159      * specified string.  The {@code Boolean} returned represents a
 160      * true value if the string argument is not {@code null}
 161      * and is equal, ignoring case, to the string {@code "true"}.
 162      *
 163      * @param   s   a string.
 164      * @return  the {@code Boolean} value represented by the string.
 165      */
 166     public static Boolean valueOf(String s) {
 167         return parseBoolean(s) ? TRUE : FALSE;
 168     }
 169 
 170     /**
 171      * Returns a {@code String} object representing the specified
 172      * boolean.  If the specified boolean is {@code true}, then
 173      * the string {@code "true"} will be returned, otherwise the
 174      * string {@code "false"} will be returned.
 175      *
 176      * @param b the boolean to be converted
 177      * @return the string representation of the specified {@code boolean}
 178      * @since 1.4
 179      */
 180     public static String toString(boolean b) {
 181         return b ? "true" : "false";
 182     }
 183 
 184     /**
 185      * Returns a {@code String} object representing this Boolean's
 186      * value.  If this object represents the value {@code true},
 187      * a string equal to {@code "true"} is returned. Otherwise, a
 188      * string equal to {@code "false"} is returned.
 189      *
 190      * @return  a string representation of this object.
 191      */
 192     public String toString() {
 193         return value ? "true" : "false";
 194     }
 195 
 196     /**
 197      * Returns a hash code for this {@code Boolean} object.
 198      *
 199      * @return  the integer {@code 1231} if this object represents
 200      * {@code true}; returns the integer {@code 1237} if this
 201      * object represents {@code false}.
 202      */
 203     @Override
 204     public int hashCode() {
 205         return Boolean.hashCode(value);
 206     }
 207 
 208     /**
 209      * Returns a hash code for a {@code boolean} value; compatible with
 210      * {@code Boolean.hashCode()}.
 211      *
 212      * @param value the value to hash
 213      * @return a hash code value for a {@code boolean} value.
 214      * @since 1.8
 215      */
 216     public static int hashCode(boolean value) {
 217         return value ? 1231 : 1237;
 218     }
 219 
 220    /**
 221      * Returns {@code true} if and only if the argument is not
 222      * {@code null} and is a {@code Boolean} object that
 223      * represents the same {@code boolean} value as this object.
 224      *
 225      * @param   obj   the object to compare with.
 226      * @return  {@code true} if the Boolean objects represent the
 227      *          same value; {@code false} otherwise.
 228      */
 229     public boolean equals(Object obj) {
 230         if (obj instanceof Boolean) {
 231             return value == ((Boolean)obj).booleanValue();
 232         }
 233         return false;
 234     }
 235 
 236     /**
 237      * Returns {@code true} if and only if the system property named
 238      * by the argument exists and is equal to the string {@code
 239      * "true"}. (Beginning with version 1.0.2 of the Java&trade;
 240      * platform, the test of this string is case insensitive.) A
 241      * system property is accessible through {@code getProperty}, a
 242      * method defined by the {@code System} class.
 243      * <p>
 244      * If there is no property with the specified name, or if the specified
 245      * name is empty or null, then {@code false} is returned.
 246      *
 247      * @param   name   the system property name.
 248      * @return  the {@code boolean} value of the system property.
 249      * @throws  SecurityException for the same reasons as
 250      *          {@link System#getProperty(String) System.getProperty}
 251      * @see     java.lang.System#getProperty(java.lang.String)
 252      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
 253      */
 254     public static boolean getBoolean(String name) {
 255         boolean result = false;
 256         try {
 257             result = parseBoolean(System.getProperty(name));
 258         } catch (IllegalArgumentException | NullPointerException e) {
 259         }
 260         return result;
 261     }
 262 
 263     /**
 264      * Compares this {@code Boolean} instance with another.
 265      *
 266      * @param   b the {@code Boolean} instance to be compared
 267      * @return  zero if this object represents the same boolean value as the
 268      *          argument; a positive value if this object represents true
 269      *          and the argument represents false; and a negative value if
 270      *          this object represents false and the argument represents true
 271      * @throws  NullPointerException if the argument is {@code null}
 272      * @see     Comparable
 273      * @since  1.5
 274      */
 275     public int compareTo(Boolean b) {
 276         return compare(this.value, b.value);
 277     }
 278 
 279     /**
 280      * Compares two {@code boolean} values.
 281      * The value returned is identical to what would be returned by:
 282      * <pre>
 283      *    Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
 284      * </pre>
 285      *
 286      * @param  x the first {@code boolean} to compare
 287      * @param  y the second {@code boolean} to compare
 288      * @return the value {@code 0} if {@code x == y};
 289      *         a value less than {@code 0} if {@code !x && y}; and
 290      *         a value greater than {@code 0} if {@code x && !y}
 291      * @since 1.7
 292      */
 293     public static int compare(boolean x, boolean y) {
 294         return (x == y) ? 0 : (x ? 1 : -1);
 295     }
 296 
 297     /**
 298      * Returns the result of applying the logical AND operator to the
 299      * specified {@code boolean} operands.
 300      *
 301      * @param a the first operand
 302      * @param b the second operand
 303      * @return the logical AND of {@code a} and {@code b}
 304      * @see java.util.function.BinaryOperator
 305      * @since 1.8
 306      */
 307     public static boolean logicalAnd(boolean a, boolean b) {
 308         return a && b;
 309     }
 310 
 311     /**
 312      * Returns the result of applying the logical OR operator to the
 313      * specified {@code boolean} operands.
 314      *
 315      * @param a the first operand
 316      * @param b the second operand
 317      * @return the logical OR of {@code a} and {@code b}
 318      * @see java.util.function.BinaryOperator
 319      * @since 1.8
 320      */
 321     public static boolean logicalOr(boolean a, boolean b) {
 322         return a || b;
 323     }
 324 
 325     /**
 326      * Returns the result of applying the logical XOR operator to the
 327      * specified {@code boolean} operands.
 328      *
 329      * @param a the first operand
 330      * @param b the second operand
 331      * @return  the logical XOR of {@code a} and {@code b}
 332      * @see java.util.function.BinaryOperator
 333      * @since 1.8
 334      */
 335     public static boolean logicalXor(boolean a, boolean b) {
 336         return a ^ b;
 337     }
 338 }
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