rt/emul/mini/src/main/java/java/lang/Boolean.java
author Jaroslav Tulach <jaroslav.tulach@apidesign.org>
Mon, 26 May 2014 14:33:42 +0200
branchclosure
changeset 1596 c5720b98ab4e
parent 1097 8e42a376da73
child 1922 2d4597793958
permissions -rw-r--r--
Special toString() method for Boolean
     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 import org.apidesign.bck2brwsr.core.JavaScriptBody;
    29 import org.apidesign.bck2brwsr.core.JavaScriptPrototype;
    30 
    31 /**
    32  * The Boolean class wraps a value of the primitive type
    33  * {@code boolean} in an object. An object of type
    34  * {@code Boolean} contains a single field whose type is
    35  * {@code boolean}.
    36  * <p>
    37  * In addition, this class provides many methods for
    38  * converting a {@code boolean} to a {@code String} and a
    39  * {@code String} to a {@code boolean}, as well as other
    40  * constants and methods useful when dealing with a
    41  * {@code boolean}.
    42  *
    43  * @author  Arthur van Hoff
    44  * @since   JDK1.0
    45  */
    46 @JavaScriptPrototype(container = "Boolean.prototype", prototype = "new Boolean")
    47 public final class Boolean implements java.io.Serializable,
    48                                       Comparable<Boolean>
    49 {
    50     /**
    51      * The {@code Boolean} object corresponding to the primitive
    52      * value {@code true}.
    53      */
    54     public static final Boolean TRUE = new Boolean(true);
    55 
    56     /**
    57      * The {@code Boolean} object corresponding to the primitive
    58      * value {@code false}.
    59      */
    60     public static final Boolean FALSE = new Boolean(false);
    61 
    62     /**
    63      * The Class object representing the primitive type boolean.
    64      *
    65      * @since   JDK1.1
    66      */
    67     public static final Class<Boolean> TYPE = Class.getPrimitiveClass("boolean");
    68 
    69     /**
    70      * The value of the Boolean.
    71      *
    72      * @serial
    73      */
    74     private final boolean value;
    75 
    76     /** use serialVersionUID from JDK 1.0.2 for interoperability */
    77     private static final long serialVersionUID = -3665804199014368530L;
    78 
    79     /**
    80      * Allocates a {@code Boolean} object representing the
    81      * {@code value} argument.
    82      *
    83      * <p><b>Note: It is rarely appropriate to use this constructor.
    84      * Unless a <i>new</i> instance is required, the static factory
    85      * {@link #valueOf(boolean)} is generally a better choice. It is
    86      * likely to yield significantly better space and time performance.</b>
    87      *
    88      * @param   value   the value of the {@code Boolean}.
    89      */
    90     public Boolean(boolean value) {
    91         this.value = value;
    92     }
    93 
    94     /**
    95      * Allocates a {@code Boolean} object representing the value
    96      * {@code true} if the string argument is not {@code null}
    97      * and is equal, ignoring case, to the string {@code "true"}.
    98      * Otherwise, allocate a {@code Boolean} object representing the
    99      * value {@code false}. Examples:<p>
   100      * {@code new Boolean("True")} produces a {@code Boolean} object
   101      * that represents {@code true}.<br>
   102      * {@code new Boolean("yes")} produces a {@code Boolean} object
   103      * that represents {@code false}.
   104      *
   105      * @param   s   the string to be converted to a {@code Boolean}.
   106      */
   107     public Boolean(String s) {
   108         this(toBoolean(s));
   109     }
   110 
   111     /**
   112      * Parses the string argument as a boolean.  The {@code boolean}
   113      * returned represents the value {@code true} if the string argument
   114      * is not {@code null} and is equal, ignoring case, to the string
   115      * {@code "true"}. <p>
   116      * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
   117      * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
   118      *
   119      * @param      s   the {@code String} containing the boolean
   120      *                 representation to be parsed
   121      * @return     the boolean represented by the string argument
   122      * @since 1.5
   123      */
   124     public static boolean parseBoolean(String s) {
   125         return toBoolean(s);
   126     }
   127 
   128     /**
   129      * Returns the value of this {@code Boolean} object as a boolean
   130      * primitive.
   131      *
   132      * @return  the primitive {@code boolean} value of this object.
   133      */
   134     @JavaScriptBody(args = {}, body = "return this.valueOf();")
   135     public boolean booleanValue() {
   136         return value;
   137     }
   138 
   139     /**
   140      * Returns a {@code Boolean} instance representing the specified
   141      * {@code boolean} value.  If the specified {@code boolean} value
   142      * is {@code true}, this method returns {@code Boolean.TRUE};
   143      * if it is {@code false}, this method returns {@code Boolean.FALSE}.
   144      * If a new {@code Boolean} instance is not required, this method
   145      * should generally be used in preference to the constructor
   146      * {@link #Boolean(boolean)}, as this method is likely to yield
   147      * significantly better space and time performance.
   148      *
   149      * @param  b a boolean value.
   150      * @return a {@code Boolean} instance representing {@code b}.
   151      * @since  1.4
   152      */
   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 toBoolean(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     public int hashCode() {
   204         return value ? 1231 : 1237;
   205     }
   206 
   207     /**
   208      * Returns {@code true} if and only if the argument is not
   209      * {@code null} and is a {@code Boolean} object that
   210      * represents the same {@code boolean} value as this object.
   211      *
   212      * @param   obj   the object to compare with.
   213      * @return  {@code true} if the Boolean objects represent the
   214      *          same value; {@code false} otherwise.
   215      */
   216     public boolean equals(Object obj) {
   217         if (obj instanceof Boolean) {
   218             return value == ((Boolean)obj).booleanValue();
   219         }
   220         return false;
   221     }
   222 
   223     /**
   224      * Returns {@code true} if and only if the system property
   225      * named by the argument exists and is equal to the string
   226      * {@code "true"}. (Beginning with version 1.0.2 of the
   227      * Java<small><sup>TM</sup></small> platform, the test of
   228      * this string is case insensitive.) A system property is accessible
   229      * through {@code getProperty}, a method defined by the
   230      * {@code System} class.
   231      * <p>
   232      * If there is no property with the specified name, or if the specified
   233      * name is empty or null, then {@code false} is returned.
   234      *
   235      * @param   name   the system property name.
   236      * @return  the {@code boolean} value of the system property.
   237      * @see     java.lang.System#getProperty(java.lang.String)
   238      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
   239      */
   240     public static boolean getBoolean(String name) {
   241         boolean result = false;
   242         try {
   243             result = toBoolean(AbstractStringBuilder.getProperty(name));
   244         } catch (IllegalArgumentException e) {
   245         } catch (NullPointerException e) {
   246         }
   247         return result;
   248     }
   249 
   250     /**
   251      * Compares this {@code Boolean} instance with another.
   252      *
   253      * @param   b the {@code Boolean} instance to be compared
   254      * @return  zero if this object represents the same boolean value as the
   255      *          argument; a positive value if this object represents true
   256      *          and the argument represents false; and a negative value if
   257      *          this object represents false and the argument represents true
   258      * @throws  NullPointerException if the argument is {@code null}
   259      * @see     Comparable
   260      * @since  1.5
   261      */
   262     public int compareTo(Boolean b) {
   263         return compare(this.value, b.value);
   264     }
   265 
   266     /**
   267      * Compares two {@code boolean} values.
   268      * The value returned is identical to what would be returned by:
   269      * <pre>
   270      *    Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
   271      * </pre>
   272      *
   273      * @param  x the first {@code boolean} to compare
   274      * @param  y the second {@code boolean} to compare
   275      * @return the value {@code 0} if {@code x == y};
   276      *         a value less than {@code 0} if {@code !x && y}; and
   277      *         a value greater than {@code 0} if {@code x && !y}
   278      * @since 1.7
   279      */
   280     public static int compare(boolean x, boolean y) {
   281         return (x == y) ? 0 : (x ? 1 : -1);
   282     }
   283 
   284     private static boolean toBoolean(String name) {
   285         return ((name != null) && name.equalsIgnoreCase("true"));
   286     }
   287     static {
   288         // as last step of initialization, initialize valueOf method
   289         initValueOf();
   290     }
   291     @JavaScriptBody(args = {  }, body = 
   292         "var bc = vm.java_lang_Boolean(false);\n" +
   293         "bc.valueOf = function() { return this._value() ? true : false; };\n" +
   294         "bc.toString = function() { return this.valueOf().toString(); };\n"
   295     )
   296     private native static void initValueOf();
   297 }