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) {
}
}
}