Java Swing - 如何最小化窗口，而不是在用户单击“x”按钮时关闭它

import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

import javax.swing.JFrame;

public class Main {
  public static void main(String[] args) throws Exception {
    Main s = new Main();
    s.start();
  }
  JFrame frame;
  public void start() {
    frame = new JFrame();
    frame.setSize(400, 400);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
    frame.addWindowListener(new myWindowListener());
  }

  class myWindowListener implements WindowListener {
    public void windowClosing(WindowEvent e) {
      frame.setState(JFrame.ICONIFIED);
    }

    public void windowActivated(WindowEvent e) {
    }

    public void windowClosed(WindowEvent e) {
    }

    public void windowDeactivated(WindowEvent e) {
    }

    public void windowDeiconified(WindowEvent e) {
    }

    public void windowIconified(WindowEvent e) {
    }

    public void windowOpened(WindowEvent e) {
    }
  }
}