Re: final variables as parameters due to action listeners

I have the following code which complains with 'Cannot refer to a
non-final variable controlPanel inside an inner class defined in a
different method':

[...]

If however I change the parameter to be final

private void addPanelListeners(final PanelAddRemove controlPanel) {

it no longer complains. I must confess I used to create a private
variable in the class as a work around which worked but was ugly.

                                                                   Now
are there any detrimental side effects to making the object final - I
assume it means dont point controlPanel to another value - but
otherwise it is fine?