Program not exiting when dispose() used.

Question

pl see the code.
I am unable exit the window if the new class Ex() is defined.
No error displayed, while running the program. What is the mistake. If anyone see please inform. No compilation error and at runtime, if Exit button is pressed, the window is not getting closed. I want to use dispose() instead of System.exit(0).
This is because, If I use System.exit(0), my menu program would also get disconnected.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
import java.io.*;
class ts extends JFrame
JPanel jpn1,jpn2,jpn3;
JButton b1,b2,b3;
JLabel jlh;
JFrame fr;
Container cp;
Connection con = null;
Choice ch1,ch2;
public ts()
final JFrame jf = new JFrame();
JPanel jpn1 = new JPanel();
jpn1.setLayout(null);
jpn1.setBackground(Color.pink);
jpn1.setPreferredSize(new Dimension(800,100));
JPanel jpn2 = new JPanel(new GridLayout(0,1));
jpn2.setPreferredSize(new Dimension(775,50));
jpn2.setBackground(Color.cyan);
jlh = new JLabel("Test Module",JLabel.CENTER);
jlh.setFont(new Font("TimesRoman",Font.BOLD,25));
jpn2.add(jlh);
JPanel jpn3 = new JPanel();
jpn3.setBackground(Color.yellow);
jpn3.setPreferredSize(new Dimension(800,50));
Container cp = jf.getContentPane();
cp.add(jpn1,BorderLayout.WEST);
cp.add(jpn2,BorderLayout.NORTH);
cp.add(jpn3,BorderLayout.SOUTH);
JButton b1 = new JButton("Get Details");
b1.setBounds(150,450,100,20);
jpn1.add(b1);
JButton b2 = new JButton("Update");
b2.setBounds(300,450,100,20);
jpn1.add(b2);
JButton b3 = new JButton("Exit");
b3.setBounds(450,450,100,20);
jpn1.add(b3);
b3.addActionListener(new Ex());
/* b3.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent e)
jf.dispose();
return;
//System.exit(0);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.setSize(800,700);
jf.setVisible(true);
//jf.pack();
jf.show();
class Ex implements ActionListener
public void actionPerformed(ActionEvent evt)
if(evt.getSource() == b3)
dispose();
return;
public static void main(String[] args)
new ts();
}

Answer 1

Your class both extends JFrame and instantiates a (separate, totally different!) JFrame. You are disposing the wrong JFrame -- and there shouldn't be two anyhow.
Since you are not modifying any default behavior of JFrame, your class has no reason to subclass JFrame. Always prefer composition over inheritance.
In future (not this time), Swing questions should be posted in the [Swing forum|http://forums.sun.com/forum.jspa?forumID=57]
db
edit And go through the [Swing Tutorial|http://java.sun.com/docs/books/tutorial/uiswing/index.html] which will (hopefully) raise your level of competence. You need more inputs than a forum can provide.
Edited by: Darryl.Burke