Making your class an event source in Java

Question

I'm making a custom button in Java that has two states, mousePressed, and mouseReleased. At the same time, if I wanted to reuse this button, so that other event listeners can register with it, are these the appropriate steps I should do (This is a hw assignment so although a JButton could be used, I think we are trying to show that we can create our own Button to act like JButton:

override addActionListener(ActionListener action)
override removeActionListener(ActionListener action)
have a private variable like List list = new List () to keep track of when events get added and some sort of function with for loop to run all the actions. Here is what I have so far:

public class CustomButton { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { CustomButtonFrame frame = new CustomButtonFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }); }
```
    public void addActionListener(ActionListener al)
    {
        listenerList.add(al);
    }

    public void removeActionListener(ActionListener al)
    {
        listenerList.remove(al);
    }

    private void notifyListeners()
    {
        for (ActionListener action : listenerList) {
            action.actionPerfomed();
        }
    }

    List<ActionListener> listenerList = new ArrayList<ActionListener>();
}
```

I'm getting the compile errors: line 38: reference to List is ambiguous, both class java.util.List in java.util and class java.awt.List in java.awt match List listenerList = new ArrayList();

and line 34: cannot find symbol, method actionPerfomed() in interface java.awt.event.ActionListener action.actionPerformed();

Does the custom button inherit from javax.swing.JButton or something similar? If this is the case, you should not have to add any custom methods at all. Otherwise, your list provides all methods needed for others to use it. — Daniel Abrahamsson
– Daniel Abrahamsson, Commented May 24, 2010 at 18:23
Could you explain if you would like to use the same button, or the same mechanizem, on another button in the same application or in another application? I will add an answer once you elaborate... — TacB0sS
– TacB0sS, Commented May 24, 2010 at 18:46

Martijn Courteaux · Accepted Answer · 2010-05-24 18:41:22Z

1

No, completely not!

A JButton has everything you need. Just add your own listener to the button. Don't override something. Just like this:

public class MyButton extends JButton implements MouseListener // maybe you want to add other listeners... separate them with comma's.
{
     public MyButton(String caption)
     {
         super(caption);
         addMouseListener(this);
     }

     // implement your listener methods here

}

answered May 24, 2010 at 18:41

Martijn Courteaux

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camickr · Accepted Answer · 2010-05-24 18:58:55Z

0

I'm making a custom button in Java that has two states, mousePressed, and mouseReleased

Maybe you should be using a JToggleButton.

answered May 24, 2010 at 18:58

camickr

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