Swing problems

[Eric Larsen]

The following code animates an oval from the top left to the bottom right of an inner class extended from JPanel. It draws and runs just fine, but then, when I click the button to redo the animation, it doesn't redraw/animate the panel. What am I doing wrong? Is it a bug or can I just not do this? Please see my other topic as well, javax.sound.midi problems, as it hasn't recieved any attention yet. Thanks in advance for the help.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Animation {

	int x = 70;
	int y = 70;

	AniDrawPanel panel = new AniDrawPanel();

	JFrame frame;

	public static void main (String [] args) {

		Animation animation = new Animation();
		animation.go();
		

	}

	public void go() {

		frame = new JFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		JButton redoButton = new JButton("Restart");
		RedoListener aniListener = new RedoListener();
		redoButton.addActionListener(aniListener);

		frame.getContentPane().add(BorderLayout.SOUTH, redoButton);
		frame.getContentPane().add(BorderLayout.CENTER, panel);

		frame.setSize(300, 300);
		frame.setVisible(true);

		aniListener.animate();

	}

	class RedoListener implements ActionListener {

		public void actionPerformed (ActionEvent ev) {

			x = 70;
			y = 70;
			this.animate();

		}

		public void animate() {

			for (int i = 0; i < 130; i++) {

				x++;
				y++;

				panel.repaint();

				try {

					Thread.sleep(50);

				} catch (Exception ex) {

					ex.printStackTrace();

				}

			}

		}

	}

	class AniDrawPanel extends JPanel {

		public void paintComponent (Graphics g) {

			g.setColor(Color.black);
			g.fillRect(0, 0, panel.getWidth(), panel.getHeight());

			g.setColor(Color.red);
			g.fillOval(x, y, 40, 40);

		}

	}

}

[Michael Dunn]

never have this type of code in Swing
Thread.sleep(50);

there is only a single thread in swing, and by 'sleeping' it, you also prevent it from repainting.
notice, when you click the button, it stays clicked for some seconds?

there are a number of ways to do your animation, simplest is using a swing.Timer

[Eric Larsen]

Oh, ok thanks! I was trying to build on some sample code in Head First Java by adding a replay button to the animation, but I didn't know that the thread.sleep() would screw it up. Thank you again!