Java MouseEvent NOBUTTON

public static final int NOBUTTON

import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
//w  ww. ja v  a  2s .  co m
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JPanel {
  JButton button = new JButton("I Move");

  public Main() {
    setLayout(null);
    add(button);
    button.setSize(button.getPreferredSize());
    button.setLocation(20, 20);
    addMouseListener(new MouseAdapter() {
      public void mousePressed(MouseEvent e) {
        System.out.println(e.getButton() == MouseEvent.NOBUTTON);
      }
    });
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame("MoveButton");
    frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
    frame.setSize(250, 200);
    frame.setLocation(200, 200);
    frame.setContentPane(new Main());
    frame.setVisible(true);
  }
}