Is it possible to use Streams.intRange function?

Question

I wanted to use Streams.intRange(int start, int end, int step) to achieve reverse ordered stream. However it seems that java.util.Streams class is no longer available (howev

Answer 1

You can create it based on an infinite stream:

public static IntStream intRange(int start, int end, int step ) {
    if ( step == 0 ) {
        throw new IllegalArgumentException("Cannot iterate with a step of zero");
    }
    final int limit = (end - start + step) / step;
    if ( limit < 0 ) {
        return IntStream.empty();
    }
    return IntStream.iterate(start, x -> x + step )
                    .limit( limit );
}

If the range doesn't make sense (e.g. range from 7 to 2 in steps of 1) you get an empty stream.

The limit is inclusive. That is, range from 2 to 8 in steps of 2 will give you 2,4,6,8. If you want it to be exclusive (without the 8), change the limit to:

final int limit = (end - start) / step;

Possible usage:

intRange(8 ,2, -2).forEach(System.out::println);

Output:

8
6
4
2