Question

Maybe it’s a bad idea, but I wrote a subclass for JMenuItem to add a new constructor. Let’s call it JMenuItemX:

import java.awt.event.ActionListener;
import javax.swing.JMenuItem;

@SuppressWarnings("serial")
public class JMenuItemX extends JMenuItem
{
  public JMenuItemX(final String the_text, final char the_mnemonic,
                    final ActionListener the_action)
  {
    super(the_text);
    setMnemonic(the_mnemonic);
    addActionListener(the_action);
  }
}

---

Now, I am trying to add a tooltip to the component by using AbstractAction:

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JOptionPane;

@SuppressWarnings("serial")
public class AboutAction extends AbstractAction
{

  public AboutAction()
  {
    super("About");
    putValue(SHORT_DESCRIPTION, "Show the popup window");
  }

  @Override
  public void actionPerformed(final ActionEvent the_event)
  {
    JOptionPane.showMessageDialog(null, "Hello World!");
  }
}

and constructing the component as so (the JFrame, JMenuBar, and JMenu are already set up):

menu.add(new JMenuItemX("About", 'a', new AboutAction()));

(As you can see, if I am adding multiple menu items, this single-line format is easier to read.)

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The menu item is visible with the correct text, and the mnemonic and action work as expected. But there is no tooltip… However, if I simply use JMenuItem, the tooltip works!

JMenuItem about = new JMenuItem(new AboutAction());
about.setMnemonic('a');
menu.add(about);

---

How can I get AbstractAction to work with my JMenuItem subclass?

Answer 1

Your overridden constructor doesn’t use the JMenuItem constructor taking an Action as argument, and doesn’t call setAction() either. So your menu item is not associated to the action.

I would not create a subclass just to add a constructor. Why not simply create a factory method?

public JMenuItem createMenuItemWithListener(String text, 
                                            char mnemonic, 
                                            ActionListener action) {
    JMenuItem result = new JMenuItem(text);
    result.setMnemonic(mnemonic);
    result.addActionListener(action);
    return result;
}

public JMenuItem createMenuItemWithAction(char mnemonic, 
                                          Action action) {
    JMenuItem result = new JMenuItem(action);
    result.setMnemonic(mnemonic);
    return result;
}