Easy way to convert Iterable to Collection

Question

In my application I use 3rd party library (Spring Data for MongoDB to be exact).

Methods of this library return Iterable, while the rest of my

Answer 1

As soon as you call contains, containsAll, equals, hashCode, remove, retainAll, size or toArray, you'd have to traverse the elements anyway.

If you're occasionally only calling methods such as isEmpty or clear I suppose you'd be better of by creating the collection lazily. You could for instance have a backing ArrayList for storing previously iterated elements.

I don't know of any such class in any library, but it should be a fairly simple exercise to write up.