Something

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class Opdracht13_02 extends Applet {
	Rechthoek c;
	Button k1, k2, k3, k4;
	
	public void init() {
		c = new Rechthoek();
		add(c);
	}
}

class Rechthoek extends Canvas {
	
	public void paint(Graphics g) { 
		int x      = 0;
		int y      = 0;
		int width  = 100;
		int height = 100;
		
		g.setColor(Color.blue);
		g.fillRect(x, y, width, height);
	}
}