– Abstract class is one which can’t be instantiated, i.e. its object cannot be created.
– Abstract method are method’s declaration without its definition.
– A Non-abstract class can only have Non-abstract methods.
– An Abstract class can have both the Non-abstract as well as Abstract methods.
– If the Class has an Abstract method then the class must also be Abstract.
– An Abstract method must be implemented by the very first Non-Abstract sub-class.
– Abstract class in Design patterns are used to encapsulate the behaviors that keeps changing.