Java get last element of a collection

Question

I have a collection, I want to get the last element of the collection. What\'s the most straighforward and fast way to do so?

One solution is to first toArray(), and

Answer 1

To avoid some of the problems mentioned above (not robust for nulls etc etc), to get first and last element in a list an approach could be

import java.util.List;

public static final <A> A getLastElement(List<A> list) {
    return list != null ? getElement(list, list.size() - 1) : null;
}

public static final <A> A getFirstElement(List<A> list) {
    return list != null ? getElement(list, 0) : null;
}   

private static final <A> A getElement(List<A> list, int pointer) {
    A res = null;
    if (list.size() > 0) {
        res = list.get(pointer);            
    }
    return res;
}

The convention adopted is that the first/last element of an empty list is null...

Answer 2

There isn't a last() or first() method in a Collection interface. For getting the last method, you can either do get(size() - 1) on a List or reverse the List and do get(0). I don't see a need to have last() method in any Collection API unless you are dealing with Stacks or Queues

Answer 3

It is not very efficient solution, but working one:

public static <T> T getFirstElement(final Iterable<T> elements) {
    return elements.iterator().next();
}

public static <T> T getLastElement(final Iterable<T> elements) {
    T lastElement = null;

    for (T element : elements) {
        lastElement = element;
    }

    return lastElement;
}

Answer 4

Iterables.getLast from Google Guava. It has some optimization for Lists and SortedSets too.