Thread: Problems with RepaintManager

I'm working on a project that draws a circle every 1000 millisec but when my loop finishes it calls the repaint manager and all my circles are removed and redrawn. Any ideas on how to prevent the repaint?

import java.awt.*;
import javax.swing.*;
import java.util.*;
import java.awt.image.*;
 
public class Forest extends JApplet {
	Random rand;
	JButton one;
	public void init() {
		setLayout(new FlowLayout());
		one = new JButton("one");
		add(one);
	}
 
	public void paint(Graphics g) {
		super.paint(g);
		int treeX = getWidth()-50, treeY=getHeight()-50, count=0;
 
 
		Graphics2D g2d = (Graphics2D) g;
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
 
		Color colorTree = new Color(randomGenerator(255),randomGenerator(255),randomGenerator(255));
			//loop for painting trees
			while(count < 3){
				wait(1000);
				paintTree(g2d,randomGenerator(treeX),randomGenerator(treeY),colorTree);
	    		colorTree = new Color(randomGenerator(255),randomGenerator(255),randomGenerator(255)); 	
	    		count = count + 1;
			}
 
 
	}
	//Method that builds tree based on random x y coordinates
	public void paintTree(Graphics2D gt, int x, int y, Color treeColor){
 
		gt.setColor(treeColor);
		gt.fillOval(x,y,50,50);
		gt.setColor(new Color(128,64,0));
		gt.fillRect((x+15),(y+47),20,40);
 
	}
	//method to return random number with upper bound passed
	public int randomGenerator(int randNum){
		rand = new Random();
		return rand.nextInt(randNum);
	}
	//wait before drawing next tree
	public void wait (int n){
        long t0,t1;
        t0=System.currentTimeMillis();
        do{
            t1=System.currentTimeMillis();
        }
        while (t1-t0<n);
	}
 
 
 
}

You can't stop the calls to the paint method. You could use a boolean flag to control what the paint method does. If the flag is not set, set it and do the drawing. Next call to paint will find the flag set and skip the drawing.
What happens if another window crosses the drawings or your frame is minimized? The contents of the screen will be changed. The call to paint will not draw your stuff.

What do I use to draw off screen? Would that be the Buffer graphic?

Look at what's called the double buffering technique. Basically it gets a BufferedImage, draws on that image and then has the paint method draw that image on the screen,