在eclipse中使用窗口构建器创建GUI时，为什么没有实现ActionListener？

Question

Im using window builder to create a front end GUI and I get the following automatically generated code. In the below code I cannot find the statement that implements ActionListener for the button click event. Its directly calling add addActionListener and actionPerformed without the statement Public class gui extends JFrame implements ActionListener as I learned in the tutorials.

public class gui extends JFrame {

    private JPanel contentPane;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    gui frame = new gui();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public gui() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 386, 451);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JButton btnNewButton = new JButton("");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
            }
        });

Answer 1

ActionListener is called as an anonymous class here:

btnNewButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
        }
    });

so your gui class doesn't need to implement it.

Answer 2

window builder always create anonymous class (for Listeners) so that you don't need to implements Listener in other class or in same class. if you dont want to use anonymous class then you have to modify the code manually.