how to unpaint my circle

i animated a circle that goes down the page and when it goes down. It does not erase the previous circle. I was wondering if there was a certain function for it.
Code:

Code:

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import javax.swing.*;
import java.awt.*;
import java.awt.geom.Ellipse2D;
public class ball extends JFrame implements Runnable {
        int y = 0;
        final int Delay = 5;
        Thread anima;
       
    public ball(){
    super("Moving Ball");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(500,500);
    setVisible(true);
    setResizable(false);
    setBackground(Color.white);
    }
    public void addNotify(){
            super.addNotify();
            anima = new Thread(this);
            anima.start();
    }
        public void paint(Graphics g){
                Graphics2D ga = (Graphics2D)g; 
                Ellipse2D e = new Ellipse2D.Float(200,y,100,100);
                ga.setColor(new Color(75,0,130));
                ga.fill(e);
            ga.draw(e);
        }
    public void cycle(){
            y++;
            if(y >= 500){
                    y = 0;
            }
    }
    public void run(){
            long starttime , total , sleep;
            starttime = System.currentTimeMillis();
            while(true){
                    cycle();
                    repaint();
                    total = System.currentTimeMillis() - starttime;
                    sleep = Delay - total;
                    if(sleep < 0){
                            sleep = 2;
                    }
                    try {
                                Thread.sleep(sleep);
                        } catch (InterruptedException e) {
                                e.printStackTrace();
                        }
                        starttime = System.currentTimeMillis();
            }
    }
    public static void main(String[] args ){
            ball b = new ball();
    }
}

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Your primary problem is that your paint method doesn't call the super.paint(g); method as its first method call. But you have other problems as well:

• You shouldn't be drawing directly in a JFrame and
• You especially shouldn't be animating in a JFrame, unless you want choppy animations.
• Instead draw/animate in a JPanel
• and do your drawing in its paintComponent method override, not its paint method.
• The first line of your paintComponent method override should be a call to the super's paintComponent method (analogous to for the paint method).
• Rather than use background threads for simple animations, consider using a Swing Timer.

Also, please check out my link on using code tags when posting code here.

Much luck!

• To improve efficiency, don't construct a new Ellipse2D every time through the painting method. Maintain one Ellipse2D as an instance field, possibly final, and mutate it before painting.
• Similarly, cache the Color(75,0,130), possibly as a static final field.

db