What is the point of using abstract methods?

Question

What\'s the point of using \"abstract methods\"? An abstract class cannot be instantiated, but what about the abstract methods? Are they just here to say \"you have to imple

Answer 1

The abstract methods merely define a contract that derived classes must implement. It's is the way how you ensure that they actually always will.

So let's take for example an abstract class Shape. It would have an abstract method draw() that should draw it. (Shape is abstract, because we do not know how to draw a general shape) By having abstract method draw in Shape we guarantee that all derived classed, that actually can be drawn, for example Circle do implement draw. Later if we forget to implement draw in some class, that is derived from Shape, compiler will actually help as giving an error.