package j7; import java.awt.event.WindowEvent; import java.awt.event.WindowAdapter; import javax.swing.JButton; import javax.swing.JFrame; public class Test extends JFrame { public static void main(String[] args) { Test t = new Test(); t.getContentPane().add(new JButton("hoge")); t.addWindowListener(new WindowAdapter() { @Override public void windowClosing(WindowEvent e) { System.exit(0); } }); t.pack(); t.setVisible(true); } }