Problems with basic Java JPanel animation using paintcomponent

Question

okay so I am trying to animate a sprite moving across a background using a for loop within the paintComponent method of a JPanel extension
public void paintComponent(Graphics g){
Image simpleBG = new ImageIcon("Images/Backgrounds/Simple path.jpg").getImage();
Image mMan = new ImageIcon("Images/Sprites/hMan.gif").getImage();
if (!backgroundIsDrawn){
g.drawImage(simpleBG, 0, 0, this);
g.drawImage(mMan, xi, y, this);
backgroundIsDrawn=true;
else
for (int i=xi; i<500; i++){
g.drawImage(simpleBG, 0, 0, this);
g.drawImage(mMan, i, y, this);
try{
Thread.sleep(10);
} catch(Exception ex){System.out.println("damn");}
The problem is that no matter what I set my thread to, it will not show the animation, it will just jump to the last location, even if the thread sleep is set high enough that it takes several minutes to calculate,, it still does not paint the intemediary steps.
any solution, including using a different method of animation all together would be greatly appreciated. I am learning java on my own so i need all the help I can get.

Answer 1

fysicsandpholds1014 wrote:
even when I placed the thread sleep outside of the actual paintComponent in a for loop that called repaint(), it still did not work? Nope. Doing this will likely put the Event Dispatch Thread or EDT to sleep. Since this is the main thread that is responsible for Swing's painting and user interaction, you'll put your app to sleep with this. Again, use a Swing Timer
and is there any easy animation method that doesnt require painting and repainting every time becasue it is very hard to change what I want to animate with a single paintComponent method? I don't get this.
I find the internet tutorials either way too complicated or not nearly in depth enough. Maybe its just that I am new to programming but there doesn't seem to be a happy medium between dumbed down Swing tutorials and very complicated and sophisticated animation algorithmns.I can only advise that you practice, practice, practice. The more you use the tutorials, the easier they'll be to use.
Here's another small demo or animation. It is not optimized (repaint is called on the whole JPanel), but demonstrates some points:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
@SuppressWarnings("serial")
public class AnimationDemo2 extends JPanel {
  // use a publicly available sprite for this example
  private static final String SPRITE_PATH = "http://upload.wikimedia.org/" +
            "wikipedia/commons/2/2e/FreeCol_flyingDutchman.png";
  private static final int SIDE = 600;
  private static final Dimension APP_SIZE = new Dimension(SIDE, SIDE);
  // timer delay: equivalent to the Thread.sleep time
  private static final int TIMER_DELAY = 20;
  // how far to move in x dimension with each loop of timer
  public static final int DELTA_X = 1;
  // holds our sprite image
  private BufferedImage img = null;
  // the images x & y locations
  private int imageX = 0;
  private int imageY = SIDE/2;
  public AnimationDemo2() {
    setPreferredSize(APP_SIZE);
    try {
      // first get our image
      URL url = new URL(SPRITE_PATH);
      img = ImageIO.read(url);
      imageY -= 3*img.getHeight()/4;
    } catch (Exception e) { // shame on me for combining exceptions :(
      e.printStackTrace();
      System.exit(1); // exit if fails
    // create and start the Swing Timer
    new Timer(TIMER_DELAY, new TimerListener()).start();
  // all paintComponent does is paint -- nothing else
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setColor(Color.blue);
    int w = getWidth();
    int h = getHeight();
    g.fillRect(0, h/2, w, h);
    if (img != null) {
      g.drawImage(img, imageX, imageY, this);
  private class TimerListener implements ActionListener {
    // is called every TIMER_DELAY ms
    public void actionPerformed(ActionEvent e) {
      imageX += DELTA_X;
      if (imageX > getWidth()) {
        imageX = 0;
      // ask JVM to paint this JPanel
      AnimationDemo2.this.repaint();
  // code to place our JPanel into a JFrame and show it
  private static void createAndShowUI() {
    JFrame frame = new JFrame("Animation Demo");
    frame.getContentPane().add(new AnimationDemo2());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  // call Swing code in a thread-safe manner
  public static void main(String[] args) {
    java.awt.EventQueue.invokeLater(new Runnable() {
      public void run() {
        createAndShowUI();
}