import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;

public class MyPanel extends JPanel {
	@Override
	protected void paintComponent(Graphics g) {
		// clean the panel
		super.paintComponent(g);
		// draw
		g.setColor(Color.RED);
		g.drawString("hello", (int) Math.round(Math.random() * this.getWidth()),
				(int) Math.round(Math.random() * this.getHeight()));
	}
}