Lambda: A constructor reference produces a Supplier or Function depending on arity

Type::new adapts to whichever functional interface it targets: a no-argument constructor fits a Supplier, while a two-argument constructor fits a BiFunction, all from the same ClassName::new syntax.

Code

class Point {
    final int x, y;
    Point() { this(0, 0); }
    Point(int x, int y) { this.x = x; this.y = y; }
    public String toString() { return "(" + x + "," + y + ")"; }
}
Supplier<Point> origin = Point::new;
BiFunction<Integer, Integer, Point> makePoint = Point::new;
System.out.println("origin: " + origin.get());
System.out.println("makePoint(2,3): " + makePoint.apply(2, 3));

Output

origin: (0,0)
makePoint(2,3): (2,3)