SoftReference.java 2.9 KB

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  1. /* java.lang.ref.SoftReference
  2. Copyright (C) 1999, 2004 Free Software Foundation, Inc.
  3. This file is part of GNU Classpath.
  4. GNU Classpath is free software; you can redistribute it and/or modify
  5. it under the terms of the GNU General Public License as published by
  6. the Free Software Foundation; either version 2, or (at your option)
  7. any later version.
  8. GNU Classpath is distributed in the hope that it will be useful, but
  9. WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. General Public License for more details.
  12. You should have received a copy of the GNU General Public License
  13. along with GNU Classpath; see the file COPYING. If not, write to the
  14. Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  15. 02110-1301 USA.
  16. Linking this library statically or dynamically with other modules is
  17. making a combined work based on this library. Thus, the terms and
  18. conditions of the GNU General Public License cover the whole
  19. combination.
  20. As a special exception, the copyright holders of this library give you
  21. permission to link this library with independent modules to produce an
  22. executable, regardless of the license terms of these independent
  23. modules, and to copy and distribute the resulting executable under
  24. terms of your choice, provided that you also meet, for each linked
  25. independent module, the terms and conditions of the license of that
  26. module. An independent module is a module which is not derived from
  27. or based on this library. If you modify this library, you may extend
  28. this exception to your version of the library, but you are not
  29. obligated to do so. If you do not wish to do so, delete this
  30. exception statement from your version. */
  31. package java.lang.ref;
  32. /**
  33. * A soft reference will be cleared, if the object is only softly
  34. * reachable and the garbage collection needs more memory. The garbage
  35. * collection will use an intelligent strategy to determine which soft
  36. * references it should clear. This makes a soft reference ideal for
  37. * caches.<br>
  38. *
  39. * @author Jochen Hoenicke
  40. */
  41. public class SoftReference<T>
  42. extends Reference<T>
  43. {
  44. /**
  45. * Create a new soft reference, that is not registered to any queue.
  46. * @param referent the object we refer to.
  47. */
  48. public SoftReference(T referent)
  49. {
  50. super(referent);
  51. }
  52. /**
  53. * Create a new soft reference.
  54. * @param referent the object we refer to.
  55. * @param q the reference queue to register on.
  56. * @exception NullPointerException if q is null.
  57. */
  58. public SoftReference(T referent, ReferenceQueue<? super T> q)
  59. {
  60. super(referent, q);
  61. }
  62. /**
  63. * Returns the object, this reference refers to.
  64. * @return the object, this reference refers to, or null if the
  65. * reference was cleared.
  66. */
  67. public T get()
  68. {
  69. /* Why is this overloaded???
  70. * Maybe for a kind of LRU strategy. */
  71. return super.get();
  72. }
  73. }