window.close ทำไง window.close ทำไง ไม่ให้มันถามว่า จะปิด มั้ยอะคับ

import javax.swing.JFrame ;
import java.awt.event.WindowEvent ;
import java.awt.event.WindowListener ;
public class T implements WindowListener {
	static JFrame f = new JFrame ( ) ;
	public static void main ( String [ ] args ) {
		new T ( ) ;
	}
	T ( ) {
		f.setDefaultCloseOperation ( 0 ) ;
		f.addWindowListener ( this ) ;
		f.setVisible ( true ) ;
	}
	public void windowActivated ( WindowEvent WE ) {
	}
	public void windowClosed ( WindowEvent WE ) {
	}
	public void windowClosing ( WindowEvent WE ) {
		new ExitDialog ( f ) ;
	}
	public void windowDeactivated ( WindowEvent WE ) {
	}
	public void windowDeiconified ( WindowEvent WE ) {
	}
	public void windowIconified ( WindowEvent WE ) {
	}
	public void windowOpened ( WindowEvent WE ) {
	}
}
class ExitDialog implements java.awt.event.ActionListener {
	static javax.swing.JDialog di = new javax.swing.JDialog ( ) ;
	static javax.swing.JLabel l = new javax.swing.JLabel ( "คุณต้องการออกจากโปรแกรมหรือไม่" , javax.swing.JLabel.CENTER ) ;
	static javax.swing.JPanel pSout = new javax.swing.JPanel ( ) ;
	static javax.swing.JButton btOK = new javax.swing.JButton ( "ตกลง" ) ;
	static javax.swing.JButton btCancle = new javax.swing.JButton ( "ยกเลิก" ) ;
	public ExitDialog ( javax.swing.JFrame MainFrame ) {
		di.setTitle ( "Exit" ) ;
		di.setLayout ( new java.awt.BorderLayout ( ) ) ;
		di.add ( l , java.awt.BorderLayout.CENTER ) ;
		di.setModal ( true ) ;
		di.setSize ( 300 , 150 ) ;
		di.setResizable ( false ) ;
		di.setLocationRelativeTo ( MainFrame ) ;
		btOK.addActionListener ( this ) ;
		btCancle.addActionListener ( this ) ;
		pSout.setLayout ( new java.awt.FlowLayout ( ) ) ;
		pSout.add ( btOK ) ;
		pSout.add ( btCancle ) ;
		di.add ( pSout , java.awt.BorderLayout.SOUTH ) ;
		di.setVisible ( true ) ;
	}
	public void actionPerformed ( java.awt.event.ActionEvent e ) {
		if ( e.getActionCommand ( ).equals ( "ตกลง" ) )
			System.exit ( 0 ) ;
		else {
			di.dispose ( ) ;
		}
	}
}