Applet loading of images -- network or JAR approach faster?

Question

hi all,
i'm stumped. my applet used to load images over the network. (it was actually designed by someone else.) yes, the applet used to load each image file independently over the network and incurred a network hit per image file.
to avoid the overhead of a separate network connection for each image file, i bundled all the images into the same JAR file that contains the applet. yet, the loading time for the applet is somehow slower now. i'm totally mystified.
i put the code for loading each image into a separate thread as well. here's the thread code:
BEGIN CODE
public class ImageLoaderThread extends Thread {
     private Hashtable images;
     private DesignApplet applet;
     public ImageLoaderThread(DesignApplet applet, Hashtable images, String imageFile) {
          super(imageFile);
          this.images = images;
          this.applet = applet;
     public void run() {
          try {
               System.out.println("Starting to load image ...");
               String imageFile = getName();
               InputStream is = applet.getClass().getResourceAsStream(imageFile);
               int arraySize = is.available() * 2; // CH: create extra space just in case
               System.out.println("Image Loader Thread: " + imageFile + "bytes available: " + arraySize);
               BufferedInputStream bis = new BufferedInputStream(is);
               byte[] byBuf = new byte[arraySize]; // a buffer large enough for our image
               int byteRead = bis.read(byBuf, 0, arraySize);
               Image buttonImage = Toolkit.getDefaultToolkit().createImage(byBuf);
               images.put(imageFile, buttonImage);
          catch(Exception e) {
               System.out.println("Exception while loading: " + getName());
               e.printStackTrace();
END CODE
imageFile is the name of an image file stored in the JAR file. it's not stored on the server anywhere, so i know the image is getting created from the JAR file. despite this, the speed of image creation seems tied to the network. in other words, when i attempt to load the applet over a slow link, it takes longer to load than over a fast link.
any ideas what i'm doing wrong? i'm seriously stumped and could use help. my goals are to minimize loading time of the applet while minimizing network hits for the server.
thanks!
p.s. if you want to play w/ the applet, click on the following link and click the "Customize" button: http://www.cengraving.com/s/z/Photo-plaques/PP024.jsp

Answer 1

Why are you using a thread to load each image why not just load the images in the gui thread?
Each thread you create takes a finite time to be started and stopped. This will surely have added to the load and startup time.
There is also blocking going on since using the Java Console I can see that each thread reports in sequence:
"Starting to load image ..."
And then after all threads have reported they are starting they then report in squence:
Image Loader Thread: " + imageFile + "bytes available: " + arraySize information.
This shows that there is at least some blocking going on with the threads.
I don't think using separate threads to do the loading is helping at all. Just load them one after another in the same thread (the thread all your threads are being started from).
The putting of the images into the images Hashtable will also be blocking since Hashtable is synchronized.