Java – removes the “first” object from the collection

In some cases, I need to expel the earliest elements in the Java collection The collection is implemented using linkedhashset, which makes it simple: just get rid of the first element returned by the collection 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 do something I can do 1 line if I use sortedset (sortedset is not an option for other reasons)

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

So is there a cleaner way?

>Change the implementation of set, or write a static practical method?

Any solution using guava is OK

I know perfectly well that sets have no inherent order I asked to delete the first entry defined by the iteration order

Solution

Linkedhashset is the wrapper of LinkedHashMap. It supports a simple "delete oldest" policy 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;
    }
});