001/* java.lang.ref.SoftReference
002   Copyright (C) 1999, 2004 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010 
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.lang.ref;
040
041/**
042 * A soft reference will be cleared, if the object is only softly
043 * reachable and the garbage collection needs more memory.  The garbage
044 * collection will use an intelligent strategy to determine which soft
045 * references it should clear.  This makes a soft reference ideal for
046 * caches.<br>
047 *
048 * @author Jochen Hoenicke 
049 */
050public class SoftReference<T>
051  extends Reference<T>
052{
053  /**
054   * Create a new soft reference, that is not registered to any queue.
055   * @param referent the object we refer to.
056   */
057  public SoftReference(T referent)
058  {
059    super(referent);
060  }
061
062  /**
063   * Create a new soft reference.
064   * @param referent the object we refer to.
065   * @param q the reference queue to register on.
066   * @exception NullPointerException if q is null.
067   */
068  public SoftReference(T referent, ReferenceQueue<? super T> q)
069  {
070    super(referent, q);
071  }
072  
073  /**
074   * Returns the object, this reference refers to.
075   * @return the object, this reference refers to, or null if the 
076   * reference was cleared.
077   */
078  public T get()
079  {
080    /* Why is this overloaded??? 
081     * Maybe for a kind of LRU strategy. */
082    return super.get();
083  }
084}