Abstract classes and methods in Java, Inheritance

Question

I have class B, which inherits from class A. The superclass A is abstract, containing one abstract method. I don\'t want to implement the abstract method in class B, therefore I

Answer 1

You are right, the two cases are equivalent. Case 1) is more simple, case 2) is code duplication - avoid it. But there may be one reason to do so:

If the method in class A does not return String but lets say C, class B may override it (since Java 5) with a more specific return type, lets say D (class extends C):

public abstract class A {
  public abstract C giveSum();
}

public abstract class B extends A {
  public abstract D giveSum();
}

public class C {
  ...
}

public class D extends C {
  ...
}