import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JOptionPane;



public class myTest{

public static void main(String[] args){

JPanel panel = new JPanel();

JButton button1 = new JButton();

panel.add(button1);

  button1.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {
	    JOptionPane.showMessageDialog(null, "Hello World");

            }
        });

}

}