Java common utilities to get list size and last object

Even if it'开发者_高级运维s easy to make an handle make, but I wonder if there is any famous helper help to get the size of a list or to get the last object of a list. I think it is really a popular requirements, but I couldn't found one.

size = list==null? 0: list.size();
lastObject = isEmpty(list)? null:list.get(list.size() - 1).

Thanks,

Those don't seem all that helpful to me. I try to initialize my lists so they're not null, so the first one is not useful at all. As for the second, it's no more useful to get back a possibly-null object (which then has to be tested to see if it's null) than it is to check the size of the list first.

There isn't a helper method for this AFAIK. One thing you should make sure is that when writing your own helper utility, pay special attention to your target collection. If it is a List, avoid using get(index) since it is not very efficient for a linked list implementation. If it is an ArrayList or in general any collection which implements RandomAccess, get is very efficient. The most generic way would be to obtain an iterator for the last element and invoke next() on it if it exists.

public static <T> T getLast(final List<T> list) {
    final ListIterator<T> listIterator = list.listIterator(list.size());
    return listIterator.hasPrevious() ? listIterator.previous() : null;
}

Google Guava has a getLast method. However, I couldn't find a size method that handles null Collections.