Argument-local inner class in Java

pdebarra

Still studying for SCJP. This question is shorter, though!

Given the following code, which all compiles just fine, my question is how I access the overridden doStuff() method:

class MyWonderfulClass {
	void go(){
		Bar b = new Bar();
		
		b.doStuff(new Foo(){
			public void foof(){
				System.out.println("Doing foofy stuff");
			}//end foof() method
		});//end new inner class
	}//end go()
}//end class

interface Foo{
	void foof();
}

class Bar{
	void doStuff(Foo f){
		System.out.println("doStuff() not overridden!!");
	}
}

I did attempt to do the following, but it only calls the original, not the overridden version of doStuff():

public class MWCTester {
	public static void main(String [] args){
		MyWonderfulClass mwc = new MyWonderfulClass();
		mwc.go();    //attempting to call overridden doStuff() method 
	}
}

marco_polo

It is not possible to call an overidden method in java.

pdebarra

marco_polo wrote: »

It is not possible to call an overidden method in java.

I disagree. Given a class Dog, as below, and a class Terrier, which extends Dog, the Terrier class overrides Dog's bark() method. When we call bark() on a Terrier, we call the overridden method.

class Dog{
	public void bark(){
		System.out.println("Woof woof");
	}
}

class Terrier extends Dog{
	public void bark(){
		System.out.println("Yap yap");
	}
}

public class DogTester{
	public static void main(String[] args){
		Dog d1 = new Dog();
		Terrier t1 = new Terrier();
		
		d1.bark();
		t1.bark();
	}
}

What I'm trying to find out is how to cause the overridden method foof() from the anonymous inner class within MyWonderfulClass, above, to execute.

Civilian_Target

It's not clear to me what you're trying to do. Where's the overwrite?

If you declare an annoymous inner class in a method, you can only execute it from that method. (Unless you use some nasty reflection tricks).

pdebarra

Ah! Got it. Silly me. I hadn't properly understood what I was at.

I should have referred to the overridden foof() method, instead of the overridden doStuff() method.

In any case, the Bar class needed one minor modification in order to actually call the new foof() method:

class Bar{
	void doStuff(Foo f){
		f.foof(); 	//new line inserted to ensure that 
					//foof() is actually called on 
					//the new Foo object.
	}
}

This will indeed print

Doing foofy stuff

Many thanks for replies.

marco_polo

pdebarra wrote: »

I disagree. Given a class Dog, as below, and a class Terrier, which extends Dog, the Terrier class overrides Dog's bark() method. When we call bark() on a Terrier, we call the overridden method.

Oops I didn't fully read your post fully , so you were not trying to do what I asumed you were.

I was referring to the overidden method as being the base class version, and the subclass method as the overiding method which is pretty common general usage. Strictly speaking though I guess all versions of the method are the overidden method.

Glad you got it sorted anyway

pdebarra

Hmmm... Yes, bark() in the Terrier class is the overriding method, and bark() in Dog is the overridden method...

Ah, but you can still call an overridden method :

super.bark();

oughter do it!

EDIT: Assuming that this code is in Terrier, not Dog! Think before you post, PdeB :mad: