Re: Inline Listeners

I am added listeners (DocumentListener) to a GUI component
(specifically a class that extends JTextField). I am wondernig why
listeners can be instantiated WITHOUT knowing any of the information
within the listener. For example...

            nameTextField.getDocument().addDocumentListener(
                    new DocumentListener() {
                        public void changedUpdate(DocumentEvent e) {
                            if (fireEvent) {
                                update();
                            }
                        }

                        public void insertUpdate(DocumentEvent e) {
                            if (fireEvent) {
                                update();
                            }
                        }

                        public void removeUpdate(DocumentEvent e) {
                            if (fireEvent) {
                                update();
                            }
                        }

                        private void update() {
 
dataModel.setName(nameTextField.getText());
                            commonUpdate();
                            nameTextField.verify();
                        }
                    });

This listener is added when the GUI is instantiated, however, it is
not until later that I set the dataModel. Why does this work? (I
realize this is probably a fundamental question, but since I never
understood it fully, I figured I would ask.)