How to get the last value of an ArrayList

How can I get the last value of an ArrayList?

I don't know the last index of the ArrayList.

Solution 1:

The following is part of the List interface (which ArrayList implements):

E e = list.get(list.size() - 1);

E is the element type. If the list is empty, get throws an IndexOutOfBoundsException. You can find the whole API documentation here.

Solution 2:

There isn't an elegant way in vanilla Java.

Google Guava

The Google Guava library is great - check out their Iterables class. This method will throw a NoSuchElementException if the list is empty, as opposed to an IndexOutOfBoundsException, as with the typical size()-1 approach - I find a NoSuchElementException much nicer, or the ability to specify a default:

lastElement = Iterables.getLast(iterableList);

You can also provide a default value if the list is empty, instead of an exception:

lastElement = Iterables.getLast(iterableList, null);

or, if you're using Options:

lastElementRaw = Iterables.getLast(iterableList, null);
lastElement = (lastElementRaw == null) ? Option.none() : Option.some(lastElementRaw);

Solution 3:

this should do it:

if (arrayList != null && !arrayList.isEmpty()) {
  T item = arrayList.get(arrayList.size()-1);
}