import java.awt.Button;
import java.awt.Dimension;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
public class Main extends JFrame {
public static void main(String[] args) {
Main frame = new Main();
frame.setSize(new Dimension(200, 200));
frame.add(new Button("Hello World"));
frame.addWindowListener(new WindowAdapter() {
@Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
frame.setVisible(true);
}
}