Source for gnu.java.io.ObjectIdentityWrapper

   1: /* ObjectIdentityWrapper.java -- Wrapper class used to override equals()
   2:     and hashCode() to be as discriminating as possible
   3:    Copyright (C) 1998 Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11: 
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: 
  40: package gnu.java.io;
  41: 
  42: /**
  43:    This class is a thin wrapper around <code>Object</code> that makes
  44:    the methods <code>hashCode()</code> and <code>equals(Object)</code>
  45:    as discriminating as possible.
  46: */
  47: public class ObjectIdentityWrapper
  48: {
  49: 
  50:   /**
  51:      Constructs a <code>ObjectIdentityWrapper</code> that is wrapped
  52:      around o.
  53:   */
  54:   public ObjectIdentityWrapper( Object o )
  55:   {
  56:     object = o;
  57:   }
  58: 
  59:   /**
  60:      Uses <code>System.identityHashCode(Object)</code> to compute a
  61:      hash code for the object wrapped by this
  62:      <code>ObjectIdentityWrapper</code>.
  63: 
  64:      @see java.lang.System#identityHashCode(java.lang.Object)
  65:      @see java.util.Hashtable
  66:      @see java.lang.Object#hashCode()
  67:   */
  68:   public int hashCode()
  69:   {
  70:     return System.identityHashCode( object );
  71:   }
  72: 
  73:   /**
  74:      Uses the <code>==</code> operator to test for equality between
  75:      the object wrapped by this <code>ObjectIdentityWrapper</code> and
  76:      the object wrapped by the <code>ObjectIdentityWrapper</code> o.
  77:      Returns false if o is not a <code>ObjectIdentityWrapper</code>.
  78: 
  79:      @see java.util.Hashtable
  80:      @see java.lang.Object#equals()
  81:   */
  82:   public boolean equals( Object o )
  83:   {
  84:     if( o instanceof ObjectIdentityWrapper )
  85:       return object == ((ObjectIdentityWrapper)o).object;
  86:     else
  87:       return false;
  88:   }
  89: 
  90:   public String toString()
  91:   {
  92:     return "ObjectIdentityWrapper< " + object + ", " + hashCode() + " >";
  93:   }
  94: 
  95:   /**
  96:      The <code>Object</code> wrapped by this
  97:      <code>ObjectIdentityWrapper</code>.
  98:   */
  99:   public Object object;
 100: }