Pros and Cons of Listeners as WeakReferences

Question

What are the pros and cons of keeping listeners as WeakReferences.

The big \'Pro\' of course is that:

Adding a listener as a WeakReference means the listener

Answer 1

It appears from a test program that anonymous ActionListeners will not prevent an object from being garbage collected:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;

public class ListenerGC {

private static ActionListener al = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            System.err.println("blah blah");
        }
    };
public static void main(String[] args) throws InterruptedException {

    {
        NoisyButton sec = new NoisyButton("second");
        sec.addActionListener(al);
        new NoisyButton("first");
        //sec.removeActionListener(al);
        sec = null;
    }
    System.out.println("start collect");
    System.gc( );
    System.out.println("end collect");
    Thread.sleep(1000);
    System.out.println("end program");
}

private static class NoisyButton extends JButton {
    private static final long serialVersionUID = 1L;
    private final String name;

    public NoisyButton(String name) {
        super();
        this.name = name;
    }

    @Override
    protected void finalize() throws Throwable {
        System.out.println(name + " finalized");
        super.finalize();
    }
}
}

produces:

start collect
end collect
first finalized
second finalized
end program