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 the first element returned by the set's iterator:

Set<Foo> mySet = new LinkedHashSet<Foo>();
// do stuff...
if (mySet.size() >= MAX_SET_SIZE)
{
    Iterator<Foo> iter = mySet.iterator();
    iter.next();
    iter.remove();
}

This is ugly: 3 lines to do something I could do with 1 line if I was using a SortedSet (for other reasons, a SortedSet is not an option here):

if (/*stuff*/)
{
    mySet.remove(mySet.first());
}

So is there a cleaner way of doing this, without:

• changing the Set implementation, or
• writing a static utility method?

Any solutions leveraging Guava are fine.

---

_{I am fully aware that sets do not have inherent ordering. I'm asking about removing the first entry as defined by iteration order.}

Answer 1

LinkedHashSet is a wrapper for LinkedHashMap which supports a simple "remove oldest" policy. To use it as a Set you can do

Set<String> set = Collections.newSetFromMap(new LinkedHashMap<String, Boolean>(){
    protected boolean removeEldestEntry(Map.Entry<String, Boolean> eldest) {
        return size() > MAX_ENTRIES;
    }
});