Here is the code that I have written please check what is wrong, as I am not able to display Images on canvas. I am trying to create game.
package PuyoPuyo;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
/*
* Puyo.java
*
* Created on January 1, 2007, 11:18 AM
*/
public class Puyo implements KeyListener, Runnable{
Display display;
Canvas canvas;
//Ball ball[];
final int height = 12;
final int width = 6;
final int canvas_height = height*32;
final int canvas_width = width*32;
public Image img[];
private Image doubleBuffer = null;
/** Creates new form Puyo */

public Puyo() {
initComponents();
}
private void initComponents() {
JFrame mainpuyo = new JFrame() ;
//GEN-BEGIN:initComponents
java.awt.Toolkit toolkit = Toolkit.getDefaultToolkit();

img = new Image[4];
img[0] = toolkit.getImage(this.getClass().getResource("/puyo_blue.png"));
img[1] = toolkit.getImage(this.getClass().getResource("/puyo_red.png"));
img[2] = toolkit.getImage(this.getClass().getResource("/puyo_green.png"));
img[3] = toolkit.getImage(this.getClass().getResource("/puyo_yellow.png"));

jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
jPanel1 = new javax.swing.JPanel();
mainpuyo.getContentPane().setLayout(null);
mainpuyo.setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
mainpuyo.setTitle("Puyo");
mainpuyo.setMaximizedBounds(new java.awt.Rectangle(0, 0, 368, 400));
mainpuyo.setResizable(false);
mainpuyo.pack();
mainpuyo.setSize(new java.awt.Dimension(400,500));
mainpuyo.setVisible(true);
jButton1.setText("New Game");
mainpuyo.add(jButton1);
jButton1.setBounds(270, 70, 120, 23);
jButton2.setText("Close");
mainpuyo.add(jButton2);
jButton2.setBounds(270, 120, 120, 23);

jPanel1.setBorder(new javax.swing.border.TitledBorder("Puyo Game"));
mainpuyo.add(jPanel1);
jPanel1.setBounds(20, 20, 240, 430);

jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});

canvas = new Canvas();
canvas.setBounds(20,20,240,430);
canvas.setSize(canvas_width,canvas_height);
canvas.setBackground(Color.white);
jPanel1.add(canvas);
canvas.addKeyListener(this);

}//GEN-END:initComponents

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt)
{

}
public static void main(String args[]) {
Puyo puyo = new Puyo();
}

// Variables declaration - do not modify//GEN-BEGIN:variables
private JButton jButton1;
private javax.swing.JButton jButton2;
private JPanel jPanel1;

public void keyTyped(KeyEvent arg0) {


}
public void keyPressed(KeyEvent arg0) {
int id = arg0.getKeyCode();
switch(id)
{
case(KeyEvent.VK_LEFT):
{
display.left();
}
break;
case( KeyEvent.VK_RIGHT):
{
display.right();
}
break;
case ( KeyEvent.VK_UP):
{
display.rotateup();
}
break;
case (KeyEvent.VK_DOWN):
{
display.rotatedown();
}
break;
}
}
public void keyReleased(KeyEvent arg0) {

}
protected void paint()
{
Graphics g=canvas.getGraphics();
if (doubleBuffer != null) {
// paint to double buffer
Graphics g2 = doubleBuffer.getGraphics();
g2.setColor(Color.WHITE);
g2.fillRect(0,0,canvas_width,canvas_height);
// draw the balls
drawBall(g2);
g2.dispose();
// copy double buffer to screen
g.drawImage(doubleBuffer, 0, 0, null);
}else{

doubleBuffer = canvas.createImage(canvas_width, canvas_height);
}
}
/**
* @param g2
*/
private void drawBall(Graphics g2) {
// TODO Auto-generated method stub

g2.drawImage(img[2], 6*32, 5*32, null);

}
/* (non-Javadoc)
* @see java.lang.Runnable#run()
*/
public void run() {
// TODO Auto-generated method stub

}




}