Button to Frame

How to add button to frame using Java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

///////////////////
// ThirdJava.java
//
//
// This program adds button to the frame
//
// Since no eventhandler is there 
// nothing happens when button is clicked
// 
// javac ThirdJava.java
//
// produces ThirdJava.class
//
// To execute 
// ----------
// java ThirdJava
//
//
//



public class ThirdJava
{

    private JFrame mainFrame;
       private JLabel headerLabel;
       private JLabel statusLabel;
       private JPanel controlPanel;

    private JButton submit;

    private  void prepareGUI(){
      mainFrame = new JFrame("Sandeep's Window");
      mainFrame.setSize(400,400);
      submit = new JButton(" Press Me");
      mainFrame.add(submit);
      mainFrame.setVisible(true);


    }

    

  
    
    public static void main(String[] args){
      ThirdJava sv = new ThirdJava();  
      sv.prepareGUI();

    }


  



}