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 ((s != null) && s.equalsIgnoreCase("true"));

   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 }