How can I prevent overlapping circles in a JApplet program?

[FritoTaco]

Hello,

I have this program where you run the JApplet and it makes circles at random. When you click the "Generate" button, it makes another set of random circles. The problem is, it overlaps the previous set of circles. I want the program to get rid of the previous set and I can't figure out how to do it. Thank you for your help.

import java.awt.*;
import javax.swing.*;
import java.applet.Applet;
import java.net.URL;
import java.awt.event.*;

public class MilkyWay extends JApplet implements ActionListener
{
    Button Button1;
    public void init() {
        setLayout( new FlowLayout( ) );
        // New button
        Button1 = new Button("Generate");
       
        // add button in japplet
        add(Button1);
       
        // listens for the button
        Button1.addActionListener(this);
    }
    public void drawCircle(Graphics g, int x, int y, int radi) {
        // draws a circle at x,y of radius r
        int red, green, blue;
       
        // choose random colors from rgb
        red = (int) (Math.random() * 256);
        green = (int) (Math.random() * 256);
        blue = (int) (Math.random() * 256);
       
        // set the foreground color
        g.setColor(new Color(red, green, blue));
       
        // draws the Oval
        g.fillOval(x, y, 2*radi, 2*radi);
    } // end of drawCircle
    public void paint( Graphics g ) {
        int x1, y1, radi;
        for (int i=0; i < 100; i++) {
            // displays circles in x/y coordinate boundaries
            x1 = (int) (Math.random()*800);
            y1 = (int) (Math.random()*800);
       
            // math choose random radius
            radi = 5 + (int)(Math.random()*35);
       
            // draw the circle
            drawCircle(g, x1, y1, radi);
        }
    }
   
    public void actionPerformed(ActionEvent e) {
        //repaint
        if (e.getSource() == Button1)
            repaint();
    }
}

 

[Borg]

You need to put something in your paint method to clear out the previous data. I don't have the method at the top of my head but something like a clear method on g.

 

[FritoTaco]

You need to put something in your paint method to clear out the previous data. I don't have the method at the top of my head but something like a clear method on g.

I've looked around online and come across this, would I use this? I would need to manipulate it, but I just wanted to know if you're referring to this.

public void clear(Graphics g)
    {
        // if(!clear)return; // optional
        g.setColor(getBackground());
        g.fillRect(0,0,(int)this.getWidth(),(int)this.getHeight());
        clear=true;
    }

 

[Borg]

Have a look at this thread - http://stackoverflow.com/questions/5271495/java-graphics-repaint-problem

 

[FritoTaco]

Thank you! I needed to add super.paint(g) in the paint method. This helped!