List, Linkedlist, Arraylist in Java

Question

About the List, Linkedlist and Arraylist, which one is a one way list and which one is Doubly-linked list? And how could we reverse it?

• kdabir: List is interface. Are you sure you checked the API?

Answer 1

• List
  An interface that merely defines behavior of lists.
  • ArrayList
    A List implementation, backed by an array. It is not a linked list.
  • LinkedList
    A List implementation, backed by an implementation of a doubly-linked list.

If you want a single-linked list, you'll have to write it yourself.

I should point out that making a single linked list that implements java.util.List is not easy. It requires you to have a ListIterator<E>, and part of the ListIterator specification is that you can traverse in either direction with methods hasPrevious, previous, and previousIndex. So to keep it both efficient and true to the single linked list mantra would be very difficult.

Answer 2

You can reverse any collection using Collections.reverse(..). LinkedList (and any Deque) has descendingIterator()