Converting Pair of Double into a double array

Question

I got the following structure

public class Point {
private final double x;
private final double y;
// imagine required args constructor and getter for both fields
}

Now, I have a list of those points defined.

List<Point> points = new ArrayList<>();
points.add(new Point(0,0));
points.add(new Point(0,1));
points.add(new Point(0,2));
points.add(new Point(0,3));

The data does not matter at all, just a list of points (the above is just an easy and quick example).

How can I transform this list to a array of doubles (double[] array) in a Java 8 way?

Answer 1

This should do it.

points.stream()
      .flatMapToDouble(point -> DoubleStream.of(point.getX(), point.getY()))
      .toArray();