How to properly rePaint JFrame

Question

here's my problem, i'm using Graphics to draw something, i have 4 functions to differentiate my drawing
-Outer Layer
-Inner Layer
-Shoulder Layer
-Shadow Layer
what i want to do is, show Outer Layer, then, wait for some delay, then show Inner Layer, then wait again for delay and so one for other layers
but the problem is, i don't know where to place repaint(); function properly, or i guess my code format for now won't work to delay painting
here's the main class calling the class
public static void main(String args[]) {
       ...//some irrelevant codes
        reply = JOptionPane.showConfirmDialog(null, ("Click Yes for Transparent window, No for normal Window"), "Yes or No?", JOptionPane.YES_NO_OPTION);
                if ( reply == JOptionPane.YES_OPTION )
                    Transp.createGUI();
                else
                    nonTransp.createGUI();
    } then here's the graphing code
import com.sun.awt.AWTUtilities;
import java.awt.*;
import java.awt.geom.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Transp extends JPanel{
    public Transp(){
        setPreferredSize(new Dimension(950, 600));
          setOpaque(false);
    public void paintComponent(Graphics g) {
            Graphics2D g2 = (Graphics2D) g;
                outerLayer(g2);
                try
                {Thread.sleep(2000);}
                catch(InterruptedException e){}
                repaint();
                innerLayer(g2);
                try
                {Thread.sleep(2000);}
                catch(InterruptedException e){}
                repaint();
                shoulderLayer(g2);
                try
                {Thread.sleep(2000);}
                catch(InterruptedException e){}
                repaint();
                shadowLayer(g2);
                repaint();
     public void outerLayer(Graphics2D g2){
          //some Graphing commands
     public void innerLayer (Graphics2D g2){
          //some Graphing commands
     public void shoulderLayer (Graphics2D g2){
          //some Graphing commands
     public void shadowLayer (Graphics2D g2){
          //some Graphing commands
     public static void createGUI() {
        Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
          JFrame.setDefaultLookAndFeelDecorated(true);
          JFrame frame = new JFrame("Paint Viewer");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          JPanel transparentcontentPane = new JPanel(new FlowLayout(0,1,1));
          transparentcontentPane.setOpaque(false);
          frame.setContentPane(transparentcontentPane);
          frame.setSize(950,600);
        frame.setLocation((screen.width - 950 )/2, (screen.height - 600)/2);
          frame.setVisible(true);
                Transp panel = new Transp();
                frame.add(panel);
          AWTUtilities.setWindowOpaque(frame, false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JFrame.setDefaultLookAndFeelDecorated(false);
     public static void main(String[] args) {}
}unfortunately, whats happening is, i guess, the program is waiting for paintComponent to do its job before it can show the painted lines
what should i do to make the JFrame refresh itself so i can delay the drawing per part of the graphics?

Answer 1

Never call sleep(...) on the EDT. Use a timer or a background thread and call repaint() after changing some state which will be detected in the paintComponent override to act accordingly.
More here:
http://download.oracle.com/javase/tutorial/uiswing/concurrency/index.html
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