Java how to optional override method in abstract class?

Question

Let\'s say we have a base class:

public abstract class BaseFragment extends Fragment {
    ...
    protected abstract boolean postExec();
    ...
}

Answer 1

Abstract methods purpose is to force you to implement them.

If add an abstract method in your superclass, you have to refactor your code and provide implementation; your program will be inconsistent even with default implementations - what if you need to return a custom type? I'd take my time to provide proper implementation, as I will probably need to call such methods if I added them.