ผมสร้างไว้หลายframe แต่ต้องการให้มันปิด frame เก่า เวลาเปิด frame ใหม่

package UIClass;

import java.util.Date;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JMenu;
import javax.swing.JLabel;
import java.awt.Label;
import javax.swing.JTextField;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.event.CaretListener;
import javax.swing.event.CaretEvent;
import java.awt.event.InputMethodListener;
import java.awt.event.InputMethodEvent;
import javax.swing.JButton;
import javax.swing.JOptionPane;
//import BussinessClass.DialogMessge;



public class MainWindow {
	
	
	private JFrame frame;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
	
		
		EventQueue.invokeLater(new Runnable() {			
			public void run() {
				try {
					MainWindow window = new MainWindow();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
				 
			}
		});
	}

	/**
	 * Create the application.
	 */
	public MainWindow() {
		initialize();
	}

	/**
	 * Initialize the contents of the frame.
	 */
	private void initialize() {
		frame = new JFrame();
		frame.setBounds(100, 100, 450, 300);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);
		
		JButton btnSearchData = new JButton("SearchData");
		btnSearchData.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
				
				
				SearchData SD = new SearchData();
				SD.main(null);
				
			}
		});
		btnSearchData.setBounds(88, 134, 101, 23);
		frame.getContentPane().add(btnSearchData);
		
		JButton btnExit = new JButton("Exit");
		btnExit.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				
			}
		});
		btnExit.setBounds(176, 206, 101, 23);
		frame.getContentPane().add(btnExit);
		
		JButton btnAddData = new JButton("AddData");
		btnAddData.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
				AddData AD= new AddData();
				AD.main(null);
			
				
				
			}
		});
		btnAddData.setBounds(88, 68, 101, 23);
		frame.getContentPane().add(btnAddData);
		
		JButton btnDeleteData = new JButton("DeleteData");
		btnDeleteData.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				DeleteData DD = new DeleteData();
				DD.main(null);
			}
		});
		btnDeleteData.setBounds(244, 68, 101, 23);
		frame.getContentPane().add(btnDeleteData);
		
		JButton btnEdotData = new JButton("EditData");
		btnEdotData.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
				EditData ED = new EditData();
				ED.main(null);
			}
		});
		btnEdotData.setBounds(244, 134, 101, 23);
		frame.getContentPane().add(btnEdotData);
	}
}