ReversibleCollection proposal

Henri Tremblay henri.tremblay at
Tue Apr 27 15:08:39 UTC 2021


Not sure if this will end up in the right mailing list thread but let's see.

I just read quickly the proposal and it made me think about another common
issue. I wonder if we could tackle it as well.

I will call it the "find the first element when there is only one" problem.

It happens on unordered collections like a HashSet. It forces to do

Set<String> s = new HashSet<>();

if (s.size() == 1) {
    return s.iterator().next();

    // or


Which is a lot of ugliness and object instantiation just to get the first

I would be nice to have a public T findFirst() directly on Iterable<T>.
With a default implementation returning iterator().next(). Things like
ArrayList will want to override will return elementData[0]. It would return
null when the list is empty. Or NoSuchElementException.

It needs to be polished of course but will that be acceptable?


More information about the core-libs-dev mailing list