Best way to get value from Collection by index

Question

What is the best way to get value from java.util.Collection by index?

Answer 1

you definitively want a List:

The List interface provides four methods for positional (indexed) access to list elements. Lists (like Java arrays) are zero based.

Also

Note that these operations may execute in time proportional to the index value for some implementations (the LinkedList class, for example). Thus, iterating over the elements in a > list is typically preferable to indexing through it if the caller does not know the implementation.

If you need the index in order to modify your collection you should note that List provides a special ListIterator that allow you to get the index:

List names = Arrays.asList("Davide", "Francesco", "Angelocola");
ListIterator i = names.listIterator();

while (i.hasNext()) {
    System.out.format("[%d] %s\n", i.nextIndex(), i.next());
}