Java KeyListener Help

Question

I have a question about why the following code does not work. It is suppose to recognize the left key when it is pressed and simply print Hello (just to check if the mehtod is being called). I have implemented a KeyListener and the methods that are required by the abstract class. The first class I posted is the main class. The second class enclosed between stars (*) is the GameWindow class which implements the KeyListener class.
* This is a simple game. Basic asteroids/invaders type game.
* July 22, 2008
package project3_summer_quarter;
import javax.swing.*;
* @author Someone
public class Main {
* @param args the command line arguments
public static void main(String[] args) throws InterruptedException {
final int width =800; //frame width
final int height = 600; //frame height
JFrame frame = new JFrame("::LaZeR::");
frame.setSize(width, height);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GameWindow contentPane = new GameWindow();
frame.add(contentPane);
frame.setVisible(true);
while(true){
contentPane.repaint();
pause();
contentPane.drawCrossHair();
} //end of while loop
public static void pause() {
final int durationInMilliSeconds = 30;
try {
Thread.sleep(durationInMilliSeconds);
} catch (Exception e) {
e.printStackTrace();
} // end method pause
}//end of class Main
* This class is used to create the Game window
package project3_summer_quarter;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
* @author Mandeep
public class GameWindow extends JPanel implements KeyListener{
ImageIcon backgroundImage;
private int backgroundX = 0;
private int backgroundY = 0;
private PlayerShip ship; //the player
Cursor crossHair;
GameWindow(){
super();
ship = new PlayerShip();
this.addKeyListener(this);
this.setFocusable(true);
public void drawCrossHair(){
//create a crossHair cursor
crossHair = new Cursor(Cursor.CROSSHAIR_CURSOR);
this.setCursor(crossHair);
@Override
public void paint(Graphics g){
backgroundImage = new ImageIcon("background.png");
Dimension d = getSize();//get the size of the content pane to
//set the background image width and height
//draw the player ship
g.drawImage(backgroundImage.getImage(),getX(),getY(), d.width, d.height, null);
ship.paintComponent(g);
* @return the backgroundX
@Override
public int getX() {
return backgroundX;
* @param backgroundX the backgroundX to set
public void setX(int x) {
this.backgroundX = x;
* @return the backgroundY
@Override
public int getY() {
return backgroundY;
* @param backgroundY the backgroundY to set
public void setY(int y) {
this.backgroundY = y;
public void keyTyped(KeyEvent e) {
if(e.getKeyCode() == 37){
System.out.println("Hello.");
public void keyPressed(KeyEvent e) {
public void keyReleased(KeyEvent e) {
}//end of class GameWindow
********************************************************************************************************************************************************************************************

Answer 1

someone16 wrote:
public void keyTyped(KeyEvent e) {
if(e.getKeyCode() == 37){
System.out.println("Hello.");
First, using the { code } takes will make it a lot easier (I spaced it just so it wouldn't go off on my text
Second, it's a good idea to, instead of using the number itself, use the API provided constant, for something like this:
    public void keyTyped(KeyEvent e) {
        if(e.getKeyCode() == KeyEvent.VK_LEFT){
            System.out.println("Hello.");
    }You're right that it's 37 in this case, but you'll find it easier in the future to do that.
Now, the KeyListener won't hear a thing if whatever it's listening to doesn't have focus. Are you sure it had focus when you tried that? Might it be easier if you made the Frame the KeyListener, and added it as a key listener, sending commands to the game window?
Just some thoughts that might help guide you.