Java abstract class

Abstract class using the abstract keyword decoration

Abstract classes do not necessarily have abstract methods, classes with abstract methods must be abstract classes or interfaces

Abstract classes cannot be instantiated, instantiated by specific subclasses

The subclass of an abstract class is either an abstract class or overrides all abstract methods in an abstract class

Member characteristics of abstract classes

A member variable can be either a variable or a constant. Abstract cannot modify member variables

There is a constructor method for subclasses to access the initialization of the parent class data

A member method can be either abstract or non-abstract

Java abstract class