Add window listener to a JFrame in Java

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
/*from   ww  w. j ava 2s  . c o  m*/
import javax.swing.JFrame;

public class Main extends JFrame {
  public Main() {
    setSize(400, 300);

    WindowListener wndCloser = new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    };
    addWindowListener(wndCloser);
    setVisible(true);
  }

  public static void main(String args[]) {
    new Main();
  }
}