Core Java Interview Questions :what is main purpose of abstract class?

if a class contains abstract method,that class must be declared as a abstract class. Abstract methods contains only declarations. it does not contain objects.:If a class contains abstract method,that class must be declared as a abstract class. Abstract methods contains only declarations. It does not contain objects.....:Even if a single method in a class is abstract then the class must be declared with the modifier abstract.:Abstract classes are class which provides partial implementation,so does&