@Override
	public ElementComparator<Point2> comparator() {
		return (u, v, i) -> i == 0
			? Double.compare(u._x, v._x)
			: Double.compare(u._y, v._y);
	}
Return the <em>y</em> value of the point.

@return the <em>y</em> value of the point
jenetics.ext/src/test/java/io/jenetics/ext/moea/Point2.java