An abstract class is a good choice if we are using the inheritance concept since it provides a common base class implementation to derived classes. An abstract class is also good if we want to declare non-public members. In an interface, all methods must be public.

Why abstract class is used in Java?

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. We can run abstract class in java like any other class if it has main() method.

When should I use abstract class?

An abstract class is used if you want to provide a common, implemented functionality among all the implementations of the component. Abstract classes will allow you to partially implement your class, whereas interfaces would have no implementation for any members whatsoever.