Design pattern for default implementation with empty methods

Question

Is there a specific design pattern that describes the scenario where a non-abstract default implementation is provided that implements all or some of the method

Answer 1

I believe Martin Fowler would call this a null object pattern. In his Refactoring book[1], Martin introduces null objects as such:

The essence of polymorphism is that instead of asking an object what type it is and then invoking some behavior based on the answer, you just invoke the behavior. The object, depending on its type, does the right thing. One of the less intuitive places to do this is where you have a null value in a field.

He later adds, "You benefit when many clients want to do the same thing; they can simply rely on the default null behavior." He also introduces an isNull() method for clients requiring variant behaviors.

I would agree that I sometimes see a (often abstract) implementation called an adapter. For example, in the Android framework, AnimatorListenerAdapter (source code here) is described as:

This adapter class provides empty implementations of the methods from Animator.AnimatorListener. Any custom listener that cares only about a subset of the methods of this listener can simply subclass this adapter class instead of implementing the interface directly.

[1] "Refactoring: Improving the Design of Existing Code," Chapter 9, "Simplifying Conditional Expressions," "Introduce Null Object."