Question

class SomeClass implements ActionListener
{
    public void actionPerformed(ActionEvent e)
        {
           // do something
        }
}

If I have 4 buttons, do I really need to create 4 classes to handle each?
Is there no way to use a method in the current class instead?

Answer 1

You can use an anonymous inner class. For example:

button1.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        doButton1Stuff();
    }
});
button2.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        doButton2Stuff();
    }
});

An anonymous inner class has access to all the containing class’s methods and variables, including private ones.

Alternatively, you can create one ActionListener and register it for all four buttons. The downside to this is that you then need logic inside the ActionListener to figure out which button was pressed (assuming each button does something different):

ActionListener a = new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == button1) {
            doButton1Stuff();
        }
        if (e.getSource() == button2) {
            doButton2Stuff();
        }
        ...
    }
}
button1.addActionListener(a);
button2.addActionListener(a);

Note that this example still uses an anonymous inner class, but you can also use a named class if you prefer.

Finally, with Swing you can take advantage of the Action class. Actions behave very much like ActionListeners but have several features that make GUI development easier in many cases.