To load the image in Applet

[Shiva Mohan]

Hi Keith,
I tried using MediaTracker.But still it gives NullPointerException error.I couldn�t figure out where I am making mistake.It would be nice,if you help me with that.

Here is my code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
 public class CoffeeServer extends JApplet{
     
         JRadioButton theNoSugar=new JRadioButton("No Sugar",true);
         JRadioButton theSugar=new JRadioButton(" Sugar");
      
         JRadioButton theNoCream=new JRadioButton("No cream",true);
         JRadioButton theCream=new JRadioButton("Cream");
          
         JButton dispense=new JButton("Dispense Seelction");
          
            JButton sugarPix,creamPix,cupPix;
            Image im1=null;
     
    
       public void init(){
           Container c =getContentPane();
           
             MediaTracker tracker = new MediaTracker(this);
 
           im1=this.getImage(getDocumentBase(),"C:/Documents and Settings/Mohan.RBCHRIT7/Desktop/HTML/Exercise1/images/Grocery.gif");
           tracker.addImage(im1,0);
          sugarPix = new JButton(new ImageIcon(im1));
          Image im2=getImage(getDocumentBase(), "cup.gif");
          cupPix = new JButton(new ImageIcon(im2));
          Image im3=getImage(getDocumentBase(), "cream.gif");
          creamPix = new JButton(new ImageIcon(im3));
 
 
            //Add pix to the north
         JPanel p=new JPanel();
         c.add(p,"North");
         p.setBorder(BorderFactory.createEmptyBorder(8,8,8,8));
         p.setLayout(new GridLayout(1,3,8,8));
         p.add(sugarPix);
         p.add(cupPix);
         p.add(creamPix);
 
           //add the dispensing buttons to the south
           c.add(dispense,"South");
 
           //create the central panel to hold the selectors
           JPanel center=new JPanel();
           center.setLayout(new GridLayout(1,2,5,5));
           c.add(center,"Center");
 
           //add the sugar selection buttons to the left
           p=new JPanel();
            p.setBorder(BorderFactory.createCompoundBorder(
                    BorderFactory.createTitledBorder("sugar"),
                    BorderFactory.createEmptyBorder(8,8,8,8)));
            p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
            p.add(theNoSugar);
             p.add(theSugar);
             center.add(p);
 
             //add the cream selection buttons to the left
           p=new JPanel();
            p.setBorder(BorderFactory.createCompoundBorder(
                    BorderFactory.createTitledBorder("cream"),
                    BorderFactory.createEmptyBorder(8,8,8,8)));
            p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
            p.add(theNoCream);
             p.add(theCream);
             center.add(p);
 
         //create the button groups to listen for actions.after we included this group button 
         //radio button will work nicely
         ButtonGroup left_group=new ButtonGroup();
         left_group.add(theNoSugar);
         left_group.add(theSugar);
          ButtonGroup right_group=new ButtonGroup();
         right_group.add(theNoCream);
         right_group.add(theCream);
         
         //set the dispenser to listen fro action
         dispense.addActionListener(new DispenseHandler());
     
       
              
       }
     
      class DispenseHandler implements ActionListener{
           public void actionPerformed(ActionEvent evt){
               if (theNoSugar.isSelected())
                   if(theNoCream.isSelected()){
                    creamPix.setVisible(false);
                    sugarPix.setVisible(false);
               }
                    else{
                    creamPix.setVisible(true);
                     sugarPix.setVisible(false);
                    }
               else
                     if (theSugar.isSelected())
                        if(theCream.isSelected()){
                            creamPix.setVisible(false);
                            sugarPix.setVisible(true);
                        }
                        else{
                             creamPix.setVisible(true);
                            sugarPix.setVisible(true);
                        } 
               repaint();
               }
                   
           }
            
       }

[ UD: added CODE tags ]
[ January 08, 2006: Message edited by: Ulf Dittmer ]

[Ulf Dittmer]

The code doesn't actually wait until the MediaTracker signals that it has loaded the images; that's a crucial part of using a tracker. The javadocs for MediaTracker have an example of how to do that.

As a side note, next time you post code, use the code tags to keep it nicely formatted and readable. It makes understanding the ocde much easier. The tags are accessed through the "CODE" button beneath the text entry box during posting. I have added them to this post for you.

[Shiva Mohan]

Thanks for the reply.Next time,i will follow the CODE tags.