这个压缩包里的都是超级经典的java例子

				
				
				
				Determining When an Object Is No Longer Used (Java Developers Almanac Example)
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				The Java Developers Almanac 1.4
				
				        Order this book from Amazon.
				    
				
				
				
				
				
				
				
				
				
				
				
				
				
								google_ad_client = "pub-6001183370374757";
				google_ad_width = 120;
				google_ad_height = 600;
				google_ad_format = "120x600_as";
				google_ad_channel = "4777242811";
				google_ad_type = "text_image";
				google_color_border = "FFFFFF";
				google_color_bg = "FFFFFF";
				google_color_link = "6666CC";
				google_color_url = "6666CC";
				google_color_text = "000000";
				//-->   
				
				Home
				    >
				    List of Packages
				    >
				
				    
				    java.lang.ref
				         [3 examples]
				    
				
				  e107. Determining When an Object Is No Longer Used
				
				A weak reference is used to determine when an object
				is no longer being referenced.
				
				    // Create the weak reference.
				    ReferenceQueue rq = new ReferenceQueue();
				    WeakReference wr = new WeakReference(object, rq);
				    
				    // Wait for all the references to the object.
				    try {
				        while (true) {
				            Reference r = rq.remove();
				            if (r == wr) {
				                // Object is no longer referenced.
				            }
				        }
				    } catch (InterruptedException e) {
				    }
				
				
				
				
				             Related Examples
				
				
				
				
				e106. 
				    Holding onto an Object Until Memory Becomes Low
				
				
				
				e108. 
				    Determining When an Object Will Be Reclaimed
				
				
				
				
				
				
				
				
				© 2002 Addison-Wesley.