Google Guava：谓词assertTrue

Question

I am looking for a method to assure all objects contained in a Collect ( List ) return a specified value from a predicate.

Pseudo Code:

Collections.assertTrue(List<Ballons>, isBluePredicate)

I do not see this being possible with the current API (maybe I am not looking in the proper place)

If this does exist would the function exit when it first encounters a false value?

Answer 1

The Iterables.all(Iterable, Predicate) method is the normal way to do this; the assertion would need to be your own.

Answer 2

Guava itself does not have any asserts. If I understand the question right you should be able to use Iterables.all

assert Iterables.all(balloonsList, isBlue) : "some aren't blue";

Documentation does not clarify whether the predicate is evaluated for rest of elements if one results in false, but I suspect they won't be. You can trivially check the source.

If you do need it to be evaluated for all elements then you should use filter and check the size of the result.