Full Window when run the program.

I want my program to open in full maximized mode while users run the program (like Firefox, Internet Explorer etc.). I hope you understood what I mean. Please help me to code this. Below is a simple code.

Code :

import javax.swing.*;
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
 
/**
 *
 * @author Faysal
 */
public class Panel extends JFrame {
 
    public Panel() {
        super("Main Window Title");
    }
 
 
 
 
    public static void main(String args[]) {
 
        Panel p1 = new Panel();
 
        p1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        
        p1.setVisible(true);
        p1.setResizable(true);
        p1.setSize(400, 500);
        //   I think I should add something here. Please help.
 
    }
 
}

Thanks in advance.