Thread: Making an image move with arrow keys

I need help with making an image of a spaceship move when I press an arrow key. For now, all I want to do is make the spaceship image move to the right when I press the right arrow key. Here's part of my code that I think could be the problem:

	public void paintComponent(Graphics g){
		super.paint(g);
		g.drawImage(starfield,0,5,null);
		g.drawImage(spaceship,shipx,shipy,null);
 
	}
 
	public class Keyboard implements KeyListener{
		public void keyTyped(KeyEvent event){}
		public void keyPressed(KeyEvent event){
			if(event.getKeyCode()==KeyEvent.VK_RIGHT){
				shipx++;
				repaint();
			}
		}
		public void keyReleased(KeyEvent event){}
	}

When I compile the above code in JCreator, there are no errors. It's just that the image of the spaceship doesn't move at all. I found many of examples online, but they were too complicated for me to follow. All help is greatly appreciated.

One issue: you show a KeyListener class, but you don't show code where you've added a KeyListener to a component, and that is absolutely necessary for KeyListeners to work. KeyListeners are also very persnickety in that they refuse to work if the component being listened to has the focus, and in fact if you read the Swing tutorials on them, you'll see that the creators of Swing recommend that you not use them in Swing applications but instead use Key Bindings for most situations, and in fact in this particular case, Key Bindings work great.

For example:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
 
import javax.swing.*;
 
@SuppressWarnings("serial")
public class MoveBall extends JPanel {
   private static final String UP = "UP";
   private static final String DOWN = "DOWN";
   private static final String LEFT = "LEFT";
   private static final String RIGHT = "RIGHT";
   private static final Color BACKGROUND = Color.black;
   private static final Color BALL_COLOR = Color.yellow;
   private static final int BALL_WIDTH = 30;
   private static final int PREF_WIDTH = 500;
   private static final int PREF_HEIGHT = PREF_WIDTH;
   private static final Dimension PREF_SIZE = new Dimension(PREF_WIDTH, PREF_HEIGHT);
   private int x = PREF_WIDTH / 2;
   private int y = PREF_HEIGHT / 2;
 
   public MoveBall() {
      setBackground(BACKGROUND);
 
      int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
      InputMap inputMap = getInputMap(condition);
      ActionMap actionMap = getActionMap();
 
      inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), UP);
      actionMap.put(UP, new AbstractAction() {
         public void actionPerformed(ActionEvent arg0) {
            y--;
            repaint();
         }
      });
 
      inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), DOWN);
      actionMap.put(DOWN, new AbstractAction() {
         public void actionPerformed(ActionEvent arg0) {
            y++;
            repaint();
         }
      });
 
      // etc for left and right
 
   }
 
   @Override
   protected void paintComponent(Graphics g) {
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D) g;
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
      g2.setColor(BALL_COLOR);
      g2.fillOval(x - BALL_WIDTH / 2, y - BALL_WIDTH / 2, 
            BALL_WIDTH, BALL_WIDTH);
   }
 
   @Override
   public Dimension getPreferredSize() {
      return PREF_SIZE;
   }
 
   private static void createAndShowGui() {
      JFrame frame = new JFrame("Move Ball");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new MoveBall());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
 
   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}