Problem with focus

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John Stivenson - 09 Jan 2005 15:39 GMT

I have two JButtons b1 and b2 on JPanel. Initially, b1 is enabled and b2
is disabled.
When the user clicks on b1 the following code is executed:

b1.setEnabled(false);
b2.setEnabled(true);
b2.requestFocusInWindow();

But b2 don't receive the focus. It seems that b1 is still focus owner.
Neighter of them now receives keyboard input. Maybe parent JPanel lost focus?

Where is the problem?

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Andrey Kuznetsov - 09 Jan 2005 18:58 GMT

> b1.setEnabled(false);
> b2.setEnabled(true);
> b2.requestFocusInWindow();

I don't know JButton.requestFocusInWindow();

> Where is the problem?

may be in your code

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Andrey Kuznetsov
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Andrew Thompson - 09 Jan 2005 20:00 GMT

>> Where is the problem?
> may be in your code

Speaking of which, here are some handy tips in case you cannot
resolve the problem and need to post code.
<http://www.physci.org/codes/sscce.jsp>

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John McGrath - 11 Jan 2005 02:50 GMT

> I don't know JButton.requestFocusInWindow();

The requestFocusInWindow() method is defined in the Component class.
It was part of the focus model changes in JDK 1.4.

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Regards,

John McGrath

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Andrey Kuznetsov - 11 Jan 2005 02:58 GMT

>> I don't know JButton.requestFocusInWindow();
>
> The requestFocusInWindow() method is defined in the Component class.
> It was part of the focus model changes in JDK 1.4.

this explains why i didn't found it in javadoc 1.3

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Andrey Kuznetsov
http://uio.dev.java.net Unified I/O for Java
http://reader.imagero.com Java image reader
http://jgui.imagero.com Java GUI components and utilities

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John McGrath - 11 Jan 2005 02:50 GMT

> I have two JButtons b1 and b2 on JPanel. Initially, b1 is enabled and b2
> is disabled. When the user clicks on b1 the following code is executed:
[quoted text clipped - 6 lines]
> Neighter of them now receives keyboard input. Maybe parent JPanel lost
> focus?

That looks like it should work. Can you post a runnable example of the
problem?

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Regards,

John McGrath

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Andrey Kuznetsov - 11 Jan 2005 03:05 GMT

>> b1.setEnabled(false);
>> b2.setEnabled(true);
>> b2.requestFocusInWindow();

in most cases it helps to pack it into Runnable and run with
SwingUtilities.invokeLater();
if it works with invokeLater then you can be sure that your sequence worked,
however _after_ it was ready something else changed focus back
so you couldn't see the result - our eyes are too slow;-)

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Andrey Kuznetsov
http://uio.dev.java.net Unified I/O for Java
http://reader.imagero.com Java image reader
http://jgui.imagero.com Java GUI components and utilities

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John McGrath - 11 Jan 2005 03:48 GMT

> >> b1.setEnabled(false);
> >> b2.setEnabled(true);
> >> b2.requestFocusInWindow();
>
> in most cases it helps to pack it into Runnable and run with
> SwingUtilities.invokeLater();

That was often required when using requestFocus() prior to JDK 1.4,
but I do not think it has been necessary since the 1.4 focus rewrite.

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Regards,

John McGrath

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Andrey Kuznetsov - 11 Jan 2005 09:31 GMT

>> >> b1.setEnabled(false);
>> >> b2.setEnabled(true);
[quoted text clipped - 5 lines]
> That was often required when using requestFocus() prior to JDK 1.4,
> but I do not think it has been necessary since the 1.4 focus rewrite.

I know at least one app where it was nesessery (yes it was JDK 1.4)

Signature

Andrey Kuznetsov
http://uio.dev.java.net Unified I/O for Java
http://reader.imagero.com Java image reader
http://jgui.imagero.com Java GUI components and utilities

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John McGrath - 11 Jan 2005 23:00 GMT

> > That was often required when using requestFocus() prior to JDK 1.4,
> > but I do not think it has been necessary since the 1.4 focus rewrite.
>
> I know at least one app where it was nesessery (yes it was JDK 1.4)

Can you explain the conditions under which it was necessary? Or better
yet, provide a runnable example of this?

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Regards,

John McGrath

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Andrey Kuznetsov - 12 Jan 2005 10:22 GMT

>> > That was often required when using requestFocus() prior to JDK 1.4,
>> > but I do not think it has been necessary since the 1.4 focus rewrite.
[quoted text clipped - 3 lines]
> Can you explain the conditions under which it was necessary? Or better
> yet, provide a runnable example of this?

you can download jgui source and search for SwingUtilities.invokeLater()
however it is used not for focus issues,
but for repacking components after undocking.

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Andrey Kuznetsov
http://uio.dev.java.net Unified I/O for Java
http://reader.imagero.com Java image reader
http://jgui.imagero.com Java GUI components and utilities

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John McGrath - 12 Jan 2005 23:04 GMT

> you can download jgui source and search for SwingUtilities.invokeLater()
> however it is used not for focus issues, but for repacking components
> after undocking.

Oh, OK. Yes, I have run into many cases where posting an action to the
event queue is necessary, including focus-shifting code before Java 1.4.
But since the 1.4 focus changes, I have not found it necessary for dealing
with focus.

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Regards,

John McGrath

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Problem with focus

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