libjava/java/lang/Boolean.java

   1 /* Boolean.java -- object wrapper for boolean
   2    Copyright (C) 1998, 2001, 2002, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.lang;
  40
  41 import java.io.Serializable;
  42
  43 /**
  44  * Instances of class <code>Boolean</code> represent primitive
  45  * <code>boolean</code> values.
  46  *
  47  * @author Paul Fisher
  48  * @author Eric Blake (ebb9@email.byu.edu)
  49  * @since 1.0
  50  * @status updated to 1.4
  51  */
  52 public final class Boolean implements Serializable
  53 {
  54   /**
  55    * Compatible with JDK 1.0.2+.
  56    */
  57   private static final long serialVersionUID = -3665804199014368530L;
  58
  59   /**
  60    * This field is a <code>Boolean</code> object representing the
  61    * primitive value <code>true</code>. This instance is returned
  62    * by the static <code>valueOf()</code> methods if they return
  63    * a <code>Boolean</code> representing <code>true</code>.
  64    */
  65   public static final Boolean TRUE = new Boolean(true);
  66
  67   /**
  68    * This field is a <code>Boolean</code> object representing the
  69    * primitive value <code>false</code>. This instance is returned
  70    * by the static <code>valueOf()</code> methods if they return
  71    * a <code>Boolean</code> representing <code>false</code>.
  72    */
  73   public static final Boolean FALSE = new Boolean(false);
  74
  75   /**
  76    * The primitive type <code>boolean</code> is represented by this
  77    * <code>Class</code> object.
  78    *
  79    * @since 1.1
  80    */
  81   public static final Class TYPE = VMClassLoader.getPrimitiveClass('Z');
  82
  83   /**
  84    * The immutable value of this Boolean.
  85    * @serial the wrapped value
  86    */
  87   private final boolean value;
  88
  89   /**
  90    * Create a <code>Boolean</code> object representing the value of the
  91    * argument <code>value</code>. In general the use of the static
  92    * method <code>valueof(boolean)</code> is more efficient since it will
  93    * not create a new object.
  94    *
  95    * @param value the primitive value of this <code>Boolean</code>
  96    * @see #valueOf(boolean)
  97    */
  98   public Boolean(boolean value)
  99   {
 100     this.value = value;
 101   }
 102
 103   /**
 104    * Creates a <code>Boolean</code> object representing the primitive
 105    * <code>true</code> if and only if <code>s</code> matches
 106    * the string "true" ignoring case, otherwise the object will represent
 107    * the primitive <code>false</code>. In general the use of the static
 108    * method <code>valueof(String)</code> is more efficient since it will
 109    * not create a new object.
 110    *
 111    * @param s the <code>String</code> representation of <code>true</code>
 112    *        or false
 113    */
 114   public Boolean(String s)
 115   {
 116     value = "true".equalsIgnoreCase(s);
 117   }
 118
 119   /**
 120    * Return the primitive <code>boolean</code> value of this
 121    * <code>Boolean</code> object.
 122    *
 123    * @return true or false, depending on the value of this Boolean
 124    */
 125   public boolean booleanValue()
 126   {
 127     return value;
 128   }
 129
 130   /**
 131    * Returns the Boolean <code>TRUE</code> if the given boolean is
 132    * <code>true</code>, otherwise it will return the Boolean
 133    * <code>FALSE</code>.
 134    *
 135    * @param b the boolean to wrap
 136    * @return the wrapper object
 137    * @see #TRUE
 138    * @see #FALSE
 139    * @since 1.4
 140    */
 141   public static Boolean valueOf(boolean b)
 142   {
 143     return b ? TRUE : FALSE;
 144   }
 145
 146   /**
 147    * Returns the Boolean <code>TRUE</code> if and only if the given
 148    * String is equal, ignoring case, to the the String "true", otherwise
 149    * it will return the Boolean <code>FALSE</code>.
 150    *
 151    * @param s the string to convert
 152    * @return a wrapped boolean from the string
 153    */
 154   public static Boolean valueOf(String s)
 155   {
 156     return "true".equalsIgnoreCase(s) ? TRUE : FALSE;
 157   }
 158
 159   /**
 160    * Returns "true" if the value of the give boolean is <code>true</code> and
 161    * returns "false" if the value of the given boolean is <code>false</code>.
 162    *
 163    * @param b the boolean to convert
 164    * @return the string representation of the boolean
 165    * @since 1.4
 166    */
 167   public static String toString(boolean b)
 168   {
 169     return b ? "true" : "false";
 170   }
 171
 172   /**
 173    * Returns "true" if the value of this object is <code>true</code> and
 174    * returns "false" if the value of this object is <code>false</code>.
 175    *
 176    * @return the string representation of this
 177    */
 178   public String toString()
 179   {
 180     return value ? "true" : "false";
 181   }
 182
 183   /**
 184    * Returns the integer <code>1231</code> if this object represents
 185    * the primitive <code>true</code> and the integer <code>1237</code>
 186    * otherwise.
 187    *
 188    * @return the hash code
 189    */
 190   public int hashCode()
 191   {
 192     return value ? 1231 : 1237;
 193   }
 194
 195   /**
 196    * If the <code>obj</code> is an instance of <code>Boolean</code> and
 197    * has the same primitive value as this object then <code>true</code>
 198    * is returned.  In all other cases, including if the <code>obj</code>
 199    * is <code>null</code>, <code>false</code> is returned.
 200    *
 201    * @param obj possibly an instance of any <code>Class</code>
 202    * @return true if <code>obj</code> equals this
 203    */
 204   public boolean equals(Object obj)
 205   {
 206     return obj instanceof Boolean && value == ((Boolean) obj).value;
 207   }
 208
 209   /**
 210    * If the value of the system property <code>name</code> matches
 211    * "true" ignoring case then the function returns <code>true</code>.
 212    *
 213    * @param name the property name to look up
 214    * @return true if the property resulted in "true"
 215    * @throws SecurityException if accessing the system property is forbidden
 216    * @see System#getProperty(String)
 217    */
 218   public static boolean getBoolean(String name)
 219   {
 220     if (name == null || "".equals(name))
 221       return false;
 222     return "true".equalsIgnoreCase(System.getProperty(name));
 223   }
 224 }