import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;

import javax.swing.JButton;
import javax.swing.JPanel;


public class PaintPanel extends JButton {
	
	Color mycolor;
	PaintPanel(){
		super();
		mycolor = new Color(255,255,0);
		this.setSize(500, 500); // THIS DOES NOT WORK
	}
	public Dimension getPreferredSize() {
	        return new Dimension(500,500); // THIS WORKS
	}
	public void paintComponent(Graphics g){
		super.paintComponents(g);
		g.setColor(Color.RED);
		g.fillRect(0, 0, 100, 100);
		g.setColor(mycolor);
		g.drawString("Hello world!", 200, 200);
	}
}