Is it possible to make a JComponent default to not-focusable?

Question

I know you can call JComponent.setFocusable(false) to make a Java component not be focusable. But since I have a LOT of components in my application that I want to be that way, I was wondering if there is a simpler way than calling it on every one of dozens of objects. Like a UIDefaults value?

I'm looking for this because my application runs full-screen and there is a KeyListener on the JFrame that listens for key strokes to trigger various events. But I found that whenever a JButton or other added component is clicked it would get the focus and the key events would never reach the JFrame. So a more elegant way to have key events be caught by a single parent container regardless of what child has the focus would also serve to fix my problem.

score 3 · Accepted Answer · answered Jul 28 '11 at 14:53

3

I was wondering if there is a simpler way than calling it on every one of dozens of objects.

I've never seen one.

there is a KeyListener on the JFrame that listens for key strokes to trigger various events.

Don't use a KeyListener.

Instead you can use JMenus and JMenuItems with accelerators. The benefit of this approach is that the key strokes are then document in the menus. See the section from the Swing tutorial on How to Use Menus.

Or if you don't like menus, then you should be using Key Bindings. They can be coded to work even if the component doesn't have focus.

answered Jul 28 '11 at 14:53

camickr

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just a small beware: menu accelerators only work as expected if they are unique - bindings with when-in-focused-window are the last to see them and only when nobody else wanted them. – kleopatra Jul 28 '11 at 15:21
I went with Key Bindings instead of the KeyListener and that did the trick. At least once I started using the JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT flag for the InputMap. – Mike O Jul 28 '11 at 16:06
@Mike, then forum procedure is to "accept" the answer that you used. – camickr Jul 28 '11 at 16:26

score 2 · Answer 2 · answered Jul 28 '11 at 15:18

2

Sounds like the job for a KeyEventDispatcher:

http://download.oracle.com/javase/6/docs/api/java/awt/KeyEventDispatcher.html

That would be solving the problem, not doctoring at not directly related properties with (incalculatable) side-effects :-)

answered Jul 28 '11 at 15:18

kleopatra

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score 1 · Answer 3 · answered Jul 28 '11 at 14:57

How about:

public boolean getComponent(Container c)
{
    Component[] cmps = c.getComponents();
    for(Component cmp : cmps)
    {
        if(cmp instanceof JComponent) // or even you could specify the JComponent you want to make it not-focusable, for example (cmp instanceof JButton)
        {
            ((JComponent)cmp).setFocusable(false);
            return true;
        }
        if(cmp instanceof Container)
        {
            if(getComponent((Container) cmp)) return true;
        }
    }
    return false;
}

Then just call it by:

getComponent(YourJFrame);

score 0 · Answer 4 · answered Jul 28 '11 at 14:57

Here is a rather crude way of walking the tree and setting it on elements you care about. Just pass in a set of noFocus (or change the logic to just be everything)...

  public static List<Component> disableFocus(final Container c, Set<Component> noFocus) {
    Component[] comps = c.getComponents();
    for (Component comp : comps) {
      if (noFucus.contains(comp) { comp.setFocusable(false); }
      if (comp instanceof Container) {
        disableFocus(comp);
      }
    }
  }

doubt that you want doctoring the symptons ;-) – kleopatra Jul 28 '11 at 15:29 — kleopatra, Jul 28 '11 at 15:29

Is it possible to make a JComponent default to not-focusable?

4 Answers4