java graphics-animation

[maki]

Hallo!

I am new in java programming and i am trying to create animation in java graphics. What i am trying to do is give motion to a simple line. The code that i have created so far is the following:

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


public class My extends JPanel implements ActionListener {


    private JFrame f;
   
    private JMenuBar jmb;
    private JMenu selectMenu;
    private JMenuItem quitItem;
    private JMenuItem againItem;
    private JMenuItem helloItem;

    private int horizontialDimension;
    private int verticalDimension;

    private int index;

    Graphics display;

    Font font;

    InnerThread in;

    Thread tr; 


    public My() {

     setSize(600,400);

     f = new JFrame("My");

     f.setSize(600, 400);

     jmb = new JMenuBar();
     selectMenu = new JMenu("Select");
     quitItem = new JMenuItem("Quit");
     againItem = new JMenuItem("Do it Again");
     helloItem = new JMenuItem("Say Hello");
     quitItem.addActionListener(this);
     againItem.addActionListener(this);
     helloItem.addActionListener(this);

     selectMenu.add(quitItem);
     selectMenu.add(againItem);
     selectMenu.add(helloItem);
     jmb.add(selectMenu);
     f.getContentPane().add(jmb, BorderLayout.NORTH);
     f.getContentPane().add(this, BorderLayout.CENTER);

     horizontialDimension = getSize().width;
     verticalDimension = getSize().height;

     f.setVisible(true);

     display = getGraphics();

     font = new Font("TimesRoman", Font.BOLD, 36);
   
     
     } 


     public void paint(Graphics g) {

       g.setColor(Color.blue);
       g.drawLine(220,100,220,120);
      //left arrow    
     
	   
    
}
     public void update(Graphics g) {
	   for (int x=220; x<300; x++){
	    int y1=(int)(x);
        int y2=(int)(x);
     
		g.drawLine(y1,100,y2,120);
        
		
 }
	           
    }

    public void actionPerformed(ActionEvent ae){

      if(ae.getSource()==quitItem) {
     
       System.exit(0);

      } else if(ae.getSource()==againItem) {

       in = new InnerThread();

       tr = new Thread(in);

       tr.start();
	   

       System.out.println("Again!!!");
     
      } else {
  
        System.out.println("Hello!!!");
 
      }

   
     }




      public static void main(String[] args){
      
       My st = new My();

       InnerThread stin = st.new InnerThread();

       Thread t = new Thread(stin);

       t.start();

      }




      public class InnerThread implements Runnable {

      
        public void run() {

           

           My.this.update(display);

            try {
 
            Thread.currentThread().sleep(100);

            } catch(InterruptedException ie) {}        

        }


      }



}

I think that the problem is in the class update. When i run the program i get a rectungle instead of a moving line. Please Help me!

[KYOrange]

in your update() code, you were not updating the line, instead, you draw a new line everytime it loop, the for loop, looped 80 times, and u drew 80 blue lines, but you forgot to clear the old line, that's why all the new lines and old lines all piled up, forming a rectangle

[maki]

The problem is that i do not know how to update the line