Creating A Cube Applet - How To Loop DrawLine

import java.awt.*;
 public class Exercise5 {
public void paint(Graphics g) {
g.drawRect(30, 50, 50, 50);
g.drawLine(30,50,40,40);
g.drawLine(80,50,90,40);
g.drawLine(40,40,90,40);
g.drawLine(80,100,90,90);
g.drawLine(90,40,90,90);
}
public static void main(String args[]) {
}
}

I got how to create the cube, but how do i loop the drawline? I am supposed to only have one ?