Source for java.lang.ref.SoftReference

   1: /* java.lang.ref.SoftReference
   2:    Copyright (C) 1999, 2004 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., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 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.ref;
  40: 
  41: /**
  42:  * A soft reference will be cleared, if the object is only softly
  43:  * reachable and the garbage collection needs more memory.  The garbage
  44:  * collection will use an intelligent strategy to determine which soft
  45:  * references it should clear.  This makes a soft reference ideal for
  46:  * caches.<br>
  47:  *
  48:  * @author Jochen Hoenicke 
  49:  */
  50: public class SoftReference<T>
  51:   extends Reference<T>
  52: {
  53:   /**
  54:    * Create a new soft reference, that is not registered to any queue.
  55:    * @param referent the object we refer to.
  56:    */
  57:   public SoftReference(T referent)
  58:   {
  59:     super(referent);
  60:   }
  61: 
  62:   /**
  63:    * Create a new soft reference.
  64:    * @param referent the object we refer to.
  65:    * @param q the reference queue to register on.
  66:    * @exception NullPointerException if q is null.
  67:    */
  68:   public SoftReference(T referent, ReferenceQueue<? super T> q)
  69:   {
  70:     super(referent, q);
  71:   }
  72:   
  73:   /**
  74:    * Returns the object, this reference refers to.
  75:    * @return the object, this reference refers to, or null if the 
  76:    * reference was cleared.
  77:    */
  78:   public T get()
  79:   {
  80:     /* Why is this overloaded??? 
  81:      * Maybe for a kind of LRU strategy. */
  82:     return super.get();
  83:   }
  84: }