What is abstract class or abstract method?
We cannot create instance for an abstract class. We can able to create
instance for its subclass only. By specifying abstract keyword just before
class, we can make a class as abstract class.
public abstract class MyAbstractClass{
}
Abstract class may or may not contains abstract methods. Abstract method is
just method signature, it does not containes any implementation. Its subclass
must provide implementation for abstract methods. Abstract methods are looks
like as given below:
public abstract int getLength();