Examples of java.lang.ref.SoftReference

java.lang.ref.SoftReference
Soft reference objects, which are cleared at the discretion of the garbage collector in response to memory demand. Soft references are most often used to implement memory-sensitive caches.
Suppose that the garbage collector determines at a certain point in time that an object is softly reachable. At that time it may choose to clear atomically all soft references to that object and all soft references to any other softly-reachable objects from which that object is reachable through a chain of strong references. At the same time or at some later time it will enqueue those newly-cleared soft references that are registered with reference queues.
All soft references to softly-reachable objects are guaranteed to have been cleared before the virtual machine throws an OutOfMemoryError. Otherwise no constraints are placed upon the time at which a soft reference will be cleared or the order in which a set of such references to different objects will be cleared. Virtual machine implementations are, however, encouraged to bias against clearing recently-created or recently-used soft references.
Direct instances of this class may be used to implement simple caches; this class or derived subclasses may also be used in larger data structures to implement more sophisticated caches. As long as the referent of a soft reference is strongly reachable, that is, is actually in use, the soft reference will not be cleared. Thus a sophisticated cache can, for example, prevent its most recently used entries from being discarded by keeping strong referents to those entries, leaving the remaining entries to be discarded at the discretion of the garbage collector. @version 1.36, 02/26/09 @author Mark Reinhold @since 1.2

   * @return a cached instance
   */
  public static SimpleFontExtensionHelper getInstance()
  {
    SimpleFontExtensionHelper instance = null;
    SoftReference instanceRef = (SoftReference) threadInstances.get();
    if (instanceRef != null)
    {
      instance = (SimpleFontExtensionHelper) instanceRef.get();
    }
    if (instance == null)
    {
      instance = new SimpleFontExtensionHelper();
      threadInstances.set(new SoftReference(instance));
    }
    return instance;
  }

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   * @return a cached instance
   */
  public static JRStyledTextParser getInstance()
  {
    JRStyledTextParser instance = null;
    SoftReference instanceRef = (SoftReference) threadInstances.get();
    if (instanceRef != null)
    {
      instance = (JRStyledTextParser) instanceRef.get();
    }
    if (instance == null)
    {
      instance = new JRStyledTextParser();
      threadInstances.set(new SoftReference(instance));
    }
    return instance;
  }

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                    // Use the same loader, allowing the new class access to
                    // same package protected members.
                    loader = (Loader) parent;
                    break getLoader;
                }
                SoftReference ref = (SoftReference) cLoaders.get(parent);
                if (ref != null) {
                    loader = (Loader) ref.get();
                    if (loader != null && loader.isValid()) {
                        break getLoader;
                    }
                    ref.clear();
                }
                loader = parent == null ? new Loader() : new Loader(parent);
                cLoaders.put(parent, new SoftReference(loader));
            }


            if (explicit) {
                reserveCheck: {
                    for (int i=0; i<2; i++) {
                        if (loader.reserveName(name)) {
                            try {
                                loader.loadClass(name);
                            } catch (ClassNotFoundException e) {
                                break reserveCheck;
                            }
                        }
                        if (i > 0) {
                            throw new IllegalStateException
                                ("Class name already reserved: " + name);
                        }
                        // Make a new loader and try again.
                        loader = parent == null ? new Loader() : new Loader(parent);
                    }


                    // Save new loader.
                    cLoaders.put(parent, new SoftReference(loader));
                }
            } else {
                for (int tryCount = 0; tryCount < 1000; tryCount++) {
                    name = null;

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    private synchronized XMLInputFactory getInputFactory() {
      XMLInputFactory inputFactory = (XMLInputFactory) factoryRef.get();
      if (inputFactory == null) {
        inputFactory = createInputFactory();
        factoryRef = new SoftReference(inputFactory);
      }
      return inputFactory;
    }

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//    }
    
    Map methods = (Map) ENCODING_METHODS.get();
    if (methods == null) {
      methods = Collections.synchronizedMap(new HashMap());
      ENCODING_METHODS = new SoftReference(methods);
    }


    Method method = (Method) methods.get(writer.getClass().getName());
    if (method == null) { // not yet cached?
      method = NOT_AVAILABLE;

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      log.debug("putFile: " + file.getName());
    }


    Map files = getOrCreateFilesystemCache(file.getFileSystem());


    Reference ref = new SoftReference(file, refqueue);
    FileSystemAndNameKey key = new FileSystemAndNameKey(file
        .getFileSystem(), file.getName());


    synchronized (files)
    {

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  {
    Map files = getOrCreateFilesystemCache(filesystem);


    synchronized (files)
    {
      SoftReference ref = (SoftReference) files.get(name);
      if (ref == null)
      {
        return null;
      }


      FileObject fo = (FileObject) ref.get();
      if (fo == null)
      {
        removeFile(filesystem, name);
      }
      return fo;

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  public void set(Object value) {
    super.set(wrap(value));
  }
  
  private static SoftReference wrap(Object value) {
    return new SoftReference(value);
  }

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    public void set(Object value) {
      super.set(wrap(value));
    }
    
    private static SoftReference wrap(Object value) {
      return new SoftReference(value);
    }

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                } else {
                    newlyCreated = true;
                    obj = _factory.makeObject();
                }
            } else {
                SoftReference ref = (SoftReference)(_pool.remove(_pool.size() - 1));
                obj = ref.get();
                ref.clear(); // prevent this ref from being enqueued with refQueue.
            }
            if (null != _factory && null != obj) {
                try {
                    _factory.activateObject(obj);
                    if (!_factory.validateObject(obj)) {

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