Java streams: count distinct values in array of primitives

Question

Why does a distinct count of an int array return a different result than a count of an Integer array? I would expect a result of 3 in both cases.

int[] numbers1 = { 1, 2, 3 };
System.out.println("numbers1: " + Arrays.toString(numbers1));
System.out.println("distinct numbers1 count: " + Stream.of(numbers1).distinct().count());

Integer[] numbers2 = { 1, 2, 3 };
System.out.println("numbers2: " + Arrays.toString(numbers2));
System.out.println("distinct numbers2 count: " + Stream.of(numbers2).distinct().count());

Results

numbers1: [1, 2, 3]
distinct numbers1 count: 1

numbers2: [1, 2, 3]
distinct numbers2 count: 3

Answer 1

In your first case, the type of Stream.of(numbers1) is Stream<int[]> and it only has one value in it.

In your second case, the type of Stream.of(numbers2) is Stream<Integer> and it has 3 distinct values in it.

You an use IntStream.of(1, 2, 3) to get a stream of primitive int.