Anonymous Classes

[Harry Singh]

HI all,
One of the questions from Mock exam :
Please select true statement(s) for an anonymous inner class
A) An anonymous class can not extend to a superclass
B) An anonymous class can not implement an interface
C) An anonymous class can extend to a superclass and implement an interface both.
D) An anonymous class can extend to a superclass or implement an interface
According to me the answer to this question should be A,B. But in answers to this mock the right answer is given as D.
HOw can anonymous class extend a class or implement a interface as this type of class dont have class name?
Thanks in advance
Regards,
Harry

[Rikko Verrijzer]

Hi Harry,
You can extend an existing class with an anymous innerclass. Take look at the following code:

new ArrayList() {
    public void myMethod() {
    }
};

for the implementing part, well if you define a new action listener you are just implementing an interface!

  
new ItemListener() {
   public void itemStateChanged(ItemEvent event) {
       //....
   }
};

If you look at it in that way, D is correct. I don't see any way to do C.
Hope this helps?
Rikko

[Thomas Paul]

An anonymous class either implicity extends a superclass OR implicitly implements an interface. It can not do both.

[Harry Singh]

Thanks Rikko,
Can u tell me more about this as i have got the idea but still im not very confident about it. How these extension of anonymous classes an be helpful in programming. Any other uses of anonymous classes apart from adapter classes.
Thanks
Harry

[Barkat Mardhani]

Hi Harry,
you can read Khalid Mogul's chapter on inner classes. It is free. I do not have website. But you can research it...
Thanks
Barkat