Swing paint method

Question

I have problem in paint method in a JPanel. At first I create a class that extends JFrame. Then I create a class that extends panel and create a object from this class and add to frame.

I want by pressing the right button on keyboard (VK_RIGHT) the little rectangles be drawn on panel Within 2 seconds. (That means rectangle clear and be drawn in a new location. My problem is: I can not do timing paint method and repaint method. I wish every two seconds rectangle go ahead for 5 times (step by step) but rectangle go ahead just one.

my codes are:

Panel

import java.awt.Color;

import java.awt.Graphics;

import javax.swing.JPanel;

public class Panel extends JPanel{

    private int x;
    private int y;
    public Panel()
    {
        x=100;
        y=100;
        this.setBackground(Color.RED);
    }

    //--------------------------------

    @Override
    public void paint(Graphics g)
    {
        super.paint(g);

        g.setColor(Color.BLACK);

        g.fillRect(x, y, 20, 20);
    }

    //--------------------------------

    @Override
    public void repaint()
    {
        super.repaint();

        x+=20;
    }

    //--------------------------------
}

Frame

import java.awt.event.KeyEvent;

import java.awt.event.KeyListener;

import javax.swing.JFrame;

public class Frame extends JFrame {

    private Panel p;

    public Frame()
    {
        super("Test");
        this.setBounds(1200, 300, 400, 400);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        p=new Panel();
        this.add(p);


        this.addKeyListener(new KeyLis());
    }

    //----------------------------------

    public static void main(String[] args) {

        Frame a=new Frame();

        a.setVisible(true);
    }

    //-----------------------------------

    private class KeyLis implements KeyListener
    {

        @Override
        public void keyPressed(KeyEvent arg0) {

            if(arg0.getKeyCode() == KeyEvent.VK_RIGHT)
            {
                for(int i=0;i<5;i++)
                {
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    p.repaint();
                }
            }
        }
        //---------------
        @Override
        public void keyReleased(KeyEvent arg0) {
            // TODO Auto-generated method stub

        }
        //---------------
        @Override
        public void keyTyped(KeyEvent arg0) {
            // TODO Auto-generated method stub

        }
        //---------------
    }
    //-----------------------------------------
}

Answer 1

If you are set on using a Thread:

Changed your KeyPressed event to:

        @Override
        public void keyPressed(KeyEvent arg0) {

            if (arg0.getKeyCode() == KeyEvent.VK_RIGHT) {
                PaintThread th = new PaintThread(p);
                th.start();
            }
        }

Created a Thread:

import java.util.logging.Level;
import java.util.logging.Logger;

public class PaintThread extends Thread{

    Panel panel;

    PaintThread(Panel panel){
        this.panel = panel;
    }

    @Override
    public void run() {
        for(int i = 0; i<5; i++){
            try {
                this.sleep(1000);
                panel.repaint();
            } catch (InterruptedException ex) {
                Logger.getLogger(PaintThread.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

}