How to get multiple values from an object using a single stream operation?

Question

I want to determine the minimum area required to display a collection of points. The easy way is to loop through the collection like this:

int minX = Integer         


        

Answer 1

You are able to use 2 Streams using Stream::reduce to get a point with a minimum and a point with a maximum. I don't recommend to concatenate the results to a one stream since there might be hard to distinguish the difference between the minimum, maximum and the coordinates.

Point min = points
    .stream()
    .reduce((l, r) -> new Point(Math.min(l.y, r.y), Math.min(l.y, r.y))
    .orElse(new Point(-1, -1));

Point max = points
    .stream()
    .reduce((l, r) -> new Point(Math.max(l.y, r.y), Math.max(l.y, r.y))
    .orElse(new Point(-1, -1));

As the BinaryOperator use the two subsequent Points and a ternary operator to find out the minimum/maximum which is passed to a new object Point and returned using Optional::orElse with the default -1, -1 coordinates.