Should I remove listeners?

Question

I don't understand if it is my responsibility to remove every listeners associated to a variable, before I set it to null.
JTable aTable = new JTable( new SomeTableModel() );
aTable = new JTable( new SomeTableModel() );Even if this example isn't very correct, as I should have done setModel on the variable, should I remove the listeners from aTable before the last statement?
In other words, should one put special care before loose a reference to a complex component?
Actually, the setModel method in JTable.java removes the old listeners, suggesting to do the same in my example.
I don't remeber where I read that Sun put a new method into one of the last jdk releases, to obtain the List of listeners.
Thanks
Enrico

Answer 1

Well, yes and no.
It is good practice to remove listeners but it is not nessecary.
The garbage collector in your case will after a unknown time notice that your program are not referencing the JTable at the moment and with that, also the table model and all other components are unreferenced from your program (read thread). Altough the JTable and table model might still reference your program, it should not care.
You might be careful thou if you for instance have an updater-thread running that slowly populates the model. If that thread is not removed, it will be referencing the table, and therefor neither thread, table or tablemodel will be garbage collected.
Regards,
Peter Norell