Some weird behaviour of my Applet

Question

I've created an applet which uses Java2D to blur an image file (image0.jpg)and display it in the browser. I can compile it with no problem but when i run the applet using the browser. The following message appears in the bottom of the browser "Start: applet not initialised". If i try to open a new window from the browser(ie. select "Window" from File>New in the menu), the applet can load successfully. The following message appears in the Java Console:
java.lang.IllegalArgumentException: Width (-1) and height (0) must be > 0
     at java.awt.image.SampleModel.<init>(Unknown Source)
     at java.awt.image.SinglePixelPackedSampleModel.<init>(Unknown Source)
     at java.awt.image.Raster.createPackedRaster(Unknown Source)
     at java.awt.image.Raster.createPackedRaster(Unknown Source)
     at java.awt.image.DirectColorModel.createCompatibleWritableRaster(Unknown Source)
     at java.awt.image.BufferedImage.<init>(Unknown Source)
     at Convolve2.init(Convolve2.java:22)
     at sun.applet.AppletPanel.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
java.lang.IllegalArgumentException: Width (-1) and height (0) must be > 0
     at java.awt.image.SampleModel.<init>(Unknown Source)
at java.awt.image.SinglePixelPackedSampleModel.<init>(Unknown Source)
     at java.awt.image.Raster.createPackedRaster(Unknown Source)
at java.awt.image.Raster.createPackedRaster(Unknown Source)
at java.awt.image.DirectColorModel.createCompatibleWritableRaster(Unknown Source)
     at java.awt.image.BufferedImage.<init>(Unknown Source)
at Convolve2.init(Convolve2.java:22)
     at sun.applet.AppletPanel.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
The following is my code. Please have a look and tell me what's wrong. Thanks a lot!
import java.awt.*;
import java.awt.image.*;
import javax.swing.*;
public class Convolve2 extends JApplet{
     float ninth = 1.0f/9.0f;
     float[] blurKernel = {
               1.5f,ninth,ninth,
               1.5f,ninth,ninth,
               ninth,ninth,1.5f,
     private Image chassis;
     private BufferedImage bChassis;
     public void init(){
          setBackground(Color.white);
          //load the image
          chassis = getImage(getDocumentBase(),"image0.jpg");
          int iw = chassis.getWidth(this);
          int ih = chassis.getHeight(this);
          //create BufferedImage as the source for image processin           bChassis = new BufferedImage(iw, ih, BufferedImage.TYPE_INT_RGB);
          Graphics2D g2d = bChassis.createGraphics();
     g2d.drawImage(chassis,0,0,this);
     public void paint(Graphics g){
          Graphics2D g2 = (Graphics2D) g;
     g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
     g2.setRenderingHint(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
          int w = bChassis.getWidth(this);
     int h = bChassis.getHeight(this);     
     //create a BufferedImage as the destination for image processing     
BufferedImage bChassis2 = new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);
          //Instantiate the operation
          ConvolveOp cop = new ConvolveOp(new Kernel(3, 3, blurKernel));
          cop.filter(bChassis,bChassis2);
          Insets insets = getInsets();
          g2.drawImage(bChassis2,insets.left, insets.top, null);

Answer 1

Your problem:
//load the image
chassis = getImage(getDocumentBase(),"image0.jpg");
int iw = chassis.getWidth(this);
int ih = chassis.getHeight(this);You forgot to prepare the image and wait until it is loaded. As long as it is not loaded, getWidth and getHeight will return -1.
Best use a MediaTracker for waiting before you query the size. Somthing like this (uncompiled on-the-fly-code):
MediaTracker mt = new MediaTracker(this);
mt.addImage(chassis, 0);
getToolkit.prepareImage(chassis, -1, -1); //prepare to be drawn at default size
mt.waitForAll();  // you'll have to catch the interrupted exceptionBye, Marc.
Toolkit.getDefaultT