15.1

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

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test_15 extends JFrame{

    public  Test_15(){
        add(new JP());
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Test_15 t = new Test_15();
        t.setTitle("test");
        t.setSize(200,200);
        t.setLocationRelativeTo(null);
        t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        t.setVisible(true);
    }

}

class JP extends JPanel{
    protected void paintComponent(Graphics g){
        super.paintComponent(g);
        
        int width = getWidth();
        int height = getHeight();    
        g.setColor(Color.BLUE);
        g.drawLine(0, height/3, width, height/3);
        g.drawLine(0, 2*height/3, width, 2*height/3);
        g.setColor(Color.RED);
        g.drawLine(width/3,0, width/3,height);
        g.drawLine(2*width/3,0, 2*width/3,height);
    }
}