Popup Menus

First the naive way I did it, then the nice way I saw posted on comp.lang.java.programmer by David Boydston.

Both ways work exactly the same from the user's point of view--They just handle mouse events differently.

If your browser supports Java 1.1, click here to see the applet run. Other browsers will do awful things.


// PopupMenuDemo1.java


import java.applet.Applet;
import java.awt.MenuItem;
import java.awt.PopupMenu;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;


// Popup menu demo.  Uses normal (delegation-based) JDK1.1 event handling,
// which in this case is less than ideal because Win32 uses mouse release
// to trigger popup menus and Solaris uses mouse down to trigger popup
// menus.  That forces us to test both mouse events for popup triggers.

public class PopupMenuDemo1 extends Applet implements ActionListener
  {


  PopupMenu menu = new PopupMenu();


  public void init()
    {
    MenuItem item;
    item = new MenuItem ("Foo");
    item.addActionListener (this);
    menu.add (item);
    item = new MenuItem ("Bar");
    item.addActionListener (this);
    menu.add (item);
    add (menu);
    addMouseListener
      (
      new MouseAdapter()
        {
        public void mousePressed (MouseEvent e) {handleMousePressed (e);}
        public void mouseReleased (MouseEvent e) {handleMouseReleased (e);}
        }
      );
    }


  // Called by the anonymous MouseAdapter to handle a mouse press.  Popup
  // triggers occur here under Solaris.

  public void handleMousePressed (MouseEvent e)
    {
    if (e.isPopupTrigger() )
      menu.show (this, e.getX(), e.getY() );
    }


  // Called by the anonymous MouseAdapter to handle a mouse release.  Popup
  // triggers occur here under Win32.

  public void handleMouseReleased (MouseEvent e)
    {
    if (e.isPopupTrigger() )
      menu.show (this, e.getX(), e.getY() );
    }


  // Someone clicked on one of the popup items.

  public void actionPerformed (ActionEvent e)
    {
    System.out.println (e.getActionCommand() );
    }


  };

See also:


// PopupMenuDemo2.java
//
// Thanks to David Boydston < daveb@sc-systems.com> for posting the Usenet
// message that made this examplet possible.


import java.applet.Applet;
import java.awt.AWTEvent;
import java.awt.MenuItem;
import java.awt.PopupMenu;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;


// Popup menu demo.  Filter all mouse events for popup triggers.  This is
// much simpler than the naive way PopupMenuDemo1.jav did it.

public class PopupMenuDemo2 extends Applet implements ActionListener
  {


  PopupMenu menu = new PopupMenu();


  public void init()
    {
    MenuItem item;
    item = new MenuItem ("Foo");
    item.addActionListener (this);
    menu.add (item);
    item = new MenuItem ("Bar");
    item.addActionListener (this);
    menu.add (item);
    add (menu);
    enableEvents (AWTEvent.MOUSE_EVENT_MASK);
    }


  // Called for every mouse event.  We need this since the popup triggers
  // occur during different mouse actions on different platforms
  // (MouseReleased on Win32, MousePressed on Solaris).

  public void processMouseEvent (MouseEvent e)
    {
    if (e.isPopupTrigger() )
      menu.show (e.getComponent(), e.getX(), e.getY() );
    super.processMouseEvent (e);
    }


  // Someone clicked on one of the popup items.

  public void actionPerformed (ActionEvent e)
    {
    System.out.println (e.getActionCommand() );
    }


  };

See also

JDK 1.1 Guide: Delegation Event Model

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