Collections - A question on iterator.

[Ritu Kapoor]

Why do we have iterators in subclasses of List interface(i.e ArrayList, Vector and LinkedList), when we can access the elements using index number?

[abhrodip paul]

Suppose you have a List of 100 elements. Do you want to retrieve all 100 elements using index method...

that is not true right. So iterator will give you fast retrieving of data from List

[Amit Y Desai]

Main reason is that when you use iterator,you never end up in any NoSuchElementException which usally arises when you use direct index to fetch a element which is not present.Its a safer way to retrive elements.

[Nadeem Khan]

Also K & B say that iterator was included in previous versions of java so its present for oldies ..no seriously book says that.

[Ritu Kapoor]

Suppose you have a List of 100 elements. Do you want to retrieve all 100 elements using index method...that is not true right.
So iterator will give you fast retrieving of data from List

Main reason is that when you use iterator,you never end up in any NoSuchElementException which usally arises when you use direct index to fetch a element which is not present.Its a safer way to retrive elements.

Well, I guess accessing by index is much faster than using Iterator and secondly, it does not throw NoSuchElementException. It throws IndexOutOfBoundsException. Please do not reply if you are confused.

My question still remains unanswered.

[Ritu Kapoor]

When I say get(index) method is better than iterators, I consider only Vector and ArrayList classes for n number of records. This does not includes LinkedList.

[Bert Bates]

Hey Ritu,

Please remember that we're all volunteering our time here at the ranch! We encourage everyone to participate in discussions of the questions that are posted here. To that end I think that this statement:

Please do not reply if you are confused.

Is probably not in the spirit of JavaRanch. Everyone in this forum is at some stage of learning Java, some know more than you and some know less, but this forum is a place for open discussions, and all sincere questions and answers must be treated with respect!

Thanks!

Bert