Re: dynamic tool tip text

From:

Jim Janney <jjanney@shell.xmission.com>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 19 Mar 2010 13:08:21 -0600

Message-ID:

<2phbocyvru.fsf@shell.xmission.com>

Jim Janney <jjanney@shell.xmission.com> writes:

Knute Johnson <nospam@rabbitbrush.frazmtn.com> writes:

On 3/18/2010 12:11 PM, Jim Janney wrote:

Knute Johnson<nospam@rabbitbrush.frazmtn.com> writes:

From: Knute Johnson<nospam@rabbitbrush.frazmtn.com>
Subject: Re: dynamic tool tip text
Newsgroups: comp.lang.java.programmer
Date: Thu, 18 Mar 2010 10:16:51 -0700
Organization: NewsDemon

On 3/18/2010 9:32 AM, Jim Janney wrote:

Thanks. That still doesn't work with a JComboBox, but that turns out
to be because nothing works with JComboBoxes, as is copiously
described in bug ID 4144505, where Sun says "yes we know, but we're
not going to fix it."

Sure it does.

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

public class test extends JPanel {
     String[] items = {"One","Two","Three","Four","Five"};

     public test() {
         super(new GridBagLayout());

         setPreferredSize(new Dimension(400,300));

         JComboBox b = new JComboBox(items);
         b.addMouseListener(new MouseAdapter() {
             public void mouseEntered(MouseEvent me) {
                 JComponent c = (JComponent)me.getSource();
                 if (me.isAltDown())
                     c.setToolTipText("ALT is pressed");
                 else
                     c.setToolTipText("ALT isn't pressed!");

             }
         });
         add(b);
     }

     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 test t = new test();
                 f.add(t);
                 f.pack();
                 f.setVisible(true);
             }
         });
     }
}

More precisely, it works on the editor but not on the button.

To be somewhat less unfair to Sun, I did find some discussion of this at

http://java.sun.com/docs/books/tutorial/uiswing/components/combobox.html#listeners

I tried this on Windows with 1.6.0_18. It works on both the box and
the arrow button. What OS and Java are you running?

Windows, java 1.6.something (I'm at home now, not at work). Try this:
Press the alt key and move the mouse into the box. The tooltip will
show "Alt is pressed". Now move the mouse back into the panel. With
the alt key released, move it into the arrow button. On my system the
tooltip shows "Alt is pressed", because there is no mouse listener on
on the arrow button. If you run this in a debugger you can also try
setting a breakpoint in the mouseEntered method.

The following code makes it work correctly in the L&Fs I've tried it with

   JComboBox b = new JComboBox(items);
   final MouseListener tooltipListener = new MouseAdapter() {
       @Override
       public void mouseEntered(MouseEvent me) {
           JComponent c = (JComponent)me.getSource();
           if (me.isAltDown())
               c.setToolTipText("ALT is pressed");
           else
               c.setToolTipText("ALT isn't pressed!");
        }
   };
   b.addMouseListener(tooltipListener);
   for (Component c : b.getComponents()) {
     if (c instanceof JComponent) {
       c.addMouseListener(tooltipListener);
     }
   }
   b.addContainerListener(new ContainerAdapter() {
     @Override
     public void componentAdded(ContainerEvent event) {
       if (event.getChild() instanceof JComponent) {
         event.getChild().addMouseListener(tooltipListener);
       }
     }
   });
   add(b);

The ContainerListener is only needed if you change the L&F
dynamically: it adds the tooltip listener to the new UI components.

--
Jim Janney