Question

What’s the best way for implementing the java.awt.event.ActionListener interface?

Have your class implement ActionListener and add this as an ActionListener:

class Foo implements ActionListener{

    public Foo() {
        JButton button = new JButton();
        button.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e) {

    }
}

Or add an object of an anonymous ActionListener class:

class Foo{

    public Foo() {
        JButton button = new JButton();
        button.addActionListener(new ActionListener() {     
            public void actionPerformed(ActionEvent e) {

            }
        });
    }
}

Answer 1

Some (jeanette/kleopatra) say to almost never use ActionListener, and to instead use Actions such as an AbstractAction. It’s almost always a bad ideal to have your GUI class implement your listeners though as this breaks the Single Responsibility Principle and makes your code more difficult to maintain and extend,and so I strongly urge you not to do that.

So for example, an inner class for this:

import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;

class Foo {

   public Foo() {
       JButton button = new JButton(new ButtonAction("Action", KeyEvent.VK_A));
   }

   private class ButtonAction extends AbstractAction {
      public ButtonAction(String name, Integer mnemonic) {
         super(name);
         putValue(MNEMONIC_KEY, mnemonic);
      }

      @Override
      public void actionPerformed(ActionEvent e) {
         System.out.println("button pressed");
      }
   }

}