Theory
About Working of abstract class:
abstract keyword is used to create a abstract class and method. Abstract class in java can't be instantiated. An abstract class is mostly used to provide a base for subclasses to extend and implement the abstract methods and override or use the implemented methods in abstract class.
Abstract class in Java is similar to interface except that it can contain default method implementation. An abstract class can have an abstract method without body and it can have methods with implementation also.
It’s not necessary for an abstract class to have abstract method. We can mark a class as abstract even if it doesn’t declare any abstract methods.
Java Abstract class can implement interfaces without even providing the implementation of interface methods.
Java Abstract class is used to provide common method implementation to all the subclasses or to provide default implementation.