Avoid overriding all abstract methods in Java

Question

I wonder if there is any way to avoid unnecessary methods from implemented interface or other class.
Let say that I have simple class implementing MouseListener, when actually I need only one method mousePressed( MouseEvent e) to override. However, in that case I also have to override every other method from interface but keep them empty like that:

public void mouseExited( MouseEvent e) {}
public void mouseClicked( MouseEvent e) {}
public void mouseReleased( MouseEvent e) {}
public void mouseEntered( MouseEvent e) {}

Is there any tricky solution to override only method I really need even when the others are abstract in interface/superclass and still keep my class as non-abstract?

JB Nizet · Accepted Answer · 2013-01-06 18:03:44Z

8

Extend MouseAdapter. It implements MouseListener by doing nothing for every method. So you can just override the one that you want.

answered Jan 6, 2013 at 18:03

JB Nizet

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4 Comments

Kamil Lelonek Over a year ago

But what if I need to extend some other class and implement a couple of interfaces?

Mickäel A. Over a year ago

You can implement an infinite number of interfaces but you can only inherit from one class. So you have to make a choice.

ldam Over a year ago

On top of that, if you want to be able to do this for any other interface you can make a dummy class that implements all of the interface methods (and does nothing with them) and then extend that class. I wouldn't recommend doing so though.

Patricia Shanahan Over a year ago

Maybe the MouseListener is trying to do too much if it needs to extend a class other than MouseAdapter and implement a couple of interfaces. Remember you can give it a constructor that takes a reference parameter, so it have have a has-a relationship to some other object.

Jean-Christophe Blanchard · Accepted Answer · 2013-01-06 18:09:45Z

1

The solution of JB Nizet is good but by the way why it is a problem ? with modern IDE like Eclipse you can add all methods to implement with just one click (source > override/implement method). If you use an adapter it's practical but you can't extend another class than the adapter.

answered Jan 6, 2013 at 18:09

Jean-Christophe Blanchard

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1 Comment

Kamil Lelonek Over a year ago

I was only wondering how to avoid unnecessary code whom I didn't use at all, but need to place in my classes.

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