Java: where should I put anonymous listener logic code?

Question

we had a debate at work about what is the best practice for using listeners in java: whether listener logic should stay in the anonymous class, or it should be in a separate method, for example:

button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        // code here
    }
});

or

button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        buttonPressed();
    }
});

private void buttonPressed() {
    // code here
}

which is the recommended way in terms of readability and maintainability? I prefer to keep the code inside the listener and only if gets too large, make it an inner class. Here I assume that the code is not duplicated anywhere else.

Thank you.

Answer 1

My self-imposed rule is:

1. If the listener has more than 2 methods, create a named class.
2. If the listener spans more than 10 lines, create a named class.

Pretty simple, easy to follow and produces more or less readable code. But then I have to admit that I never even thought of what your example shows.