If I have a simple List< Point2D > declared.
/* What I tried */
You have to create an instance of
Point2D. Right now, you are adding
null to your
listOfPoints is not initialized, so your code would generate a
NullPointerException. Try this instead:
List<Point2D> listOfPoints = new ArrayList<>(); // or another List implementation class Point2D point1 = new Point2D.Float(3, 2); // or perhaps Point2D.Double listOfPoints.add(point1);
Also, once you have a
Point2D.Double object, you can set the coordinates explicitly, either by assigning directly to the
y fields or by calling
setLocation() and passing the coordinates.