Removing the “first” object from a Set

Question

Under certain situations, I need to evict the oldest element in a Java Set. The set is implemented using a LinkedHashSet, which makes this simple: just get rid of t

Answer 1

With guava:

if (!set.isEmpty() && set.size() >= MAX_SET_SIZE) {
    set.remove(Iterables.get(set, 0));
}

I will also suggest an alternative approach. Yes, it it changing the implementation, but not drastically: extend LinkedHashSet and have that condition in the add method:

public LimitedLinkedHashSet extends LinkedHashSet {
    public void add(E element) {
         super.add(element);
         // your 5-line logic from above or my solution with guava
    }
}

It's still 5 line, but it is invisible to the code that's using it. And since this is actually a specific behaviour of the set, it is logical to have it within the set.