Iterator Interface.A question please.

Question

I am unable to grasp the meaning of the following below :
As we all know,Interfaces have abstract methods,(ie methods that
have no body) and any class that implements the Interface has to
implement the methods defined in the interface.That is,write the body for those methods.
So far so good.
Now coming to Collections called Vector.
We have the 'Iterator' interface implemented by the vector class.
The Iterator interface has the methods hasNext(),next().
and we have the following code in the our class which iterates thru'
the vector:
MyClass item;
while(iter.hasNext())
item = (MyClass)iter.next();
// Do something here.....
Now we are using the methods hasNext() and next() above.
But as they belong to the Iterator interface,(which means they
are basically methods with no implementations) then how is iteration
possible? We havent defined anything in the hasNext() method or the next()
so how does Java automatically start iteration
Has any one understood my question?Arent hasNext() and next() supposed
to be methods with no body???
If I am saying iter.hasNext(),that means hasNext() has been defined
somewhere to iterate thru the vector?
I am just confused regarding this issue as to how is hasNext() and next()
being implemented as I as the programmer have not implemented them
in my code
Please can some one answer my question?
Regards
Ajay

Answer 1

Thanks Will.
Regarding the question,then why define an Iterator interface when
the collection class implements the functionality?
Why not define the methods hasNext() and next() in the Object
class?
So by default,all classes extends the Object class ,we
cud use the hasNext() and next() method?
No??? Or am I wrong?