What is an abstract class ?

Answer 1

An abstract class is a class intended to be extended by other classes. It cannot be instantiated and it may contain abstract methods. Abstract methods are methods without a body. The body will be written in the subclass.

Abstract classes in Java by Sandra Meyer
https://code.sololearn.com/cpBBBib607tW

Answer 2

An abstract class is a restricted class that cannot be used to create objects . To access it, it must be inherited from another class.

Abstract class in Java.