import javax.swing.*;
 
public class HelloFrame extends JFrame {
	public HelloFrame() {
		setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
		add(new JLabel("Hello, world!"));
		pack();
	}
 
	public static void main(String[] args) {
		new HelloFrame().setVisible(true);
	}

	static final long serialVersionUID = -1L;
}