Re: how to remove anonymous listener?

From:

Eric Sosman <esosman@acm-dot-org.invalid>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 16 Aug 2006 22:09:52 -0400

Message-ID:

<YpCdndjH9p1jUn7ZnZ2dnUVZ_tqdnZ2d@comcast.com>

Brandon McCombs wrote:

I setup an array of combo boxes using the following (some code removed
such as layout properties):

for (int i = 0; i < cbAccountProps.length; i++) {
    cbAccountProps[i] = new JCheckBox(strAccountProps[i]);
    cbAccountProps[i].setFont(fnt2);
    cbAccountProps[i].addItemListener( new ItemListener() {
        public void itemStateChanged(ItemEvent e) {
            notifyChanges(hasAccountStatusChanged);
        }
    });
}

When I initialize the dialog window that this code is in the window is
automatically set to show that changes have been made to the user whose
properties are displayed in the dialog. This is because the data is set
while the listeners are active. I already have 2 methods that go
through disabling/enabling all document listeners (for a bunch of
textfields that are also in the dialog window). But I'm not sure how to
remove/add the anonymous inner class above in those same methods so that
when I set data upon the dialog opening it hasn't yet detected changes
programmatically, let alone by the operator of the application. I have a
feeling I will have to have a separate ItemListener class setup so that
I can declare an instance of it.

     You can still have an anonymous class, but you need to
remember a reference to the instance so you can pass it to
cbAccountProps[i].removeItemListener() later on.

    ItemListener[] snoops =
        new ItemListener[cbAccountProps.length];
    // ...
    for (int i = 0; i < cbAccountProps.length; i++) {
        // ...
        snoops[i] = new ItemListener() {
            public void itemStateChanged(ItemEvent e) {
                notifyChanges(hasAccountStatusChanged);
            }
        };
        cbAccountProps[i].addItemListener(snoops[i]);
    }

     When you want to remove them, use the array that you've
carefully remembered to do

    for (int i = 0; i < cbAccountProps.length; ++i)
        cpAccountProps[i].removeItemListener(snoops[i]);
    // safe to discard snoops now (if they won't be
    // re-activated later)

--
Eric Sosman
esosman@acm-dot-org.invalid