import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;

public class PopUpJList extends JPanel
    implements ActionListener{
 JButton jb1, jb2;
 JPopupMenu popupMenu;
 JMenuItem jmi1, jmi2;
 JList list;
 int i = 1;

 public PopUpJList(){
   Vector data;
   setLayout(new BorderLayout());
   list = new JList();
   list.setModel(new DefaultListModel());
   add(new JScrollPane(list),"Center");
   add(jb1 = new JButton("Add"), "East");
   add(jb2 = new JButton("Clear"), "West");
   jb1.addActionListener(this);
   jb2.addActionListener(this);

   popupMenu = new JPopupMenu();
   popupMenu.add(jmi1= new JMenuItem("Add"));
   popupMenu.add(new JPopupMenu.Separator());
   popupMenu.add(jmi2 = new JMenuItem("Clear"));


   list.addMouseListener(new MouseAdapter() {
     public void mouseClicked(MouseEvent me) {
       // if right mouse button clicked (or me.isPopupTrigger())
       if (SwingUtilities.isRightMouseButton(me)
           && !list.isSelectionEmpty()
           && list.locationToIndex(me.getPoint())
              == list.getSelectedIndex()) {
               popupMenu.show(list, me.getX(), me.getY());
               }
           }
        }
     );

   jmi1.addActionListener(this);
   jmi2.addActionListener(this);

   }

 public Dimension getPreferredSize(){
   return new Dimension(50, 50);
   }

 public void actionPerformed(ActionEvent ae) {
  if (ae.getSource() == jb1 || ae.getSource() == jmi1) {
     // add
     DefaultListModel dlm =
       (DefaultListModel) list.getModel();
     dlm.addElement
        ((Object) Integer.toString(i++));
     }
   else {
    // clear
    list.setModel(new DefaultListModel());
    }
  }
 public static void main(String s[]) {
   JFrame frame = new JFrame("PopUp JList");
   PopUpJList panel = new PopUpJList();
   frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
   frame.getContentPane().add(panel,"Center");

   frame.setSize(200,200);
   frame.setVisible(true);
    }
}