How to test if it is a Fibonacci Stream?

Question

This is not a fibonacci stream.

LongStream digits = LongStream.of(0, 1, 2 , 3 , 4, 5, 6, 7, 8, 9);

Neither is this.

LongStream naturals = LongStream.iterate(1,  (i) -> i + 1);

But, how do you check that they are not?

Notice that the second stream is infinite, so you need some short-circuit operation to stop as soon as possible. Unfortunately, the short-circuit methods 'allMatch' and 'anyMatch' only tests on elements, not the sequence.

Answer 1

Using Guava Iterables.elementsEqual:

Supplier<Integer> fibonacci = new Supplier<Integer>() {
        int first = 0;
        int second = 1;

        @Override
        public Integer get() {
            int result = first + second;
            first = second;
            second = result;
            return first;
        }
    };
boolean isMatch = Iterables.elementsEqual(
                     toTest, 
                     Stream.generate(fibonacci).limit(toTest.size()).collect(Collectors.toList()));