Object Pool

[Mihai Radulescu]

Hallo

I deal in a GUI with a lot images(gufs, jpgs) and because some of them are uses in more than one place I try to manage them with via a casche mechanism.
So I build a pool where I keep all my the imaget that I use(see the code below).

 
public static IconPool ICON_POOL = new IconPool();
 
   private final Map resources =  new HashMap();
   private final ReferenceQueue queue = new ReferenceQueue();
 
   private IconPool () {
   }
 
   /**
    * Search a resource in the resources inventory and retun
    * it. If the resource is not present in the inventory
    * (that means was collected by the gc) the resource is
    * created and registered in to inventory.
    *
    * @param key String        the key for the resource, most of
    * the time is the resource canonic path.
    * @param baseName String   the base name.
    * @return javax.swing.Icon the resource.
    */
   public Icon getIcon(String key, String baseName) {
 
       resloveTheQueue();
 
       SoftReference cache = (SoftReference) resources.get(key);
       if(cache == null) {
           //no resources in invetory, generate a new one.
           cache = store(key, baseName);
           resources.put(key, cache);
       }
 
       return (Icon) cache.get();
   }
 
   /**
    * Creates and saves a resource in the resources inventory.
    * @param key String t
    * @param baseName
    * @return
    */
   private SoftReference store(String key, String baseName) {
       final SoftReference cache =
               new SoftReference(new ImageHelper(key, baseName), queue);
       resources.put(key, cache);
       return cache;
   }
 
   private void resloveTheQueue() {
       for(Reference reference = null;(reference = queue.poll()) != null :wink:  {
           removeValue(reference);
       }
   }
 
   private boolean removeValue(Object value) {
       for(Iterator i = resources.keySet().iterator();i.hasNext() :wink:  {
           Object key = i.next();
           if(resources.get(key) == value) {
               resources.remove(key);
               return true;
           }
       }
       return false;
   }
 
   public Set getIconKeys() {
       return Collections.unmodifiableSet(resources.keySet());
   }
 
   public boolean freeResource(String key) {
      return resources.remove(key) == key;
   }
 
   public void freeAllResources() {
      resources.clear();
   }
 

I know that a similar map mechanism exist already for WeakReferences (java.util.WeakHashMap) but I use (explicit) the soft references for them quality - the garbage collector might clear a soft reference but always clears a weak referencen.
It this ok ? There are also other opinion about this?

[Dirk Schreckmann]

I'm moving this to the Advanced forum...
[ December 04, 2004: Message edited by: Dirk Schreckmann ]