How to get the last value of an ArrayList

2021-6-3 anglehua

How can I get the last value of an ArrayList?

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

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.

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);


Powered by emlog 京ICP备15036472号-3 sitemap