Avoiding a null pointer exception state with the null object pattern

The null object pattern provides a way to gracefully deal with an unidentified object and not cause unexpected or undefined program behavior.

Motivation

Instead of using the Java null construct to indicate the absence of an object, consider introducing the Null object pattern. A null object is considered to belong to a specific family of objects. The object implements the expected interface, but implementing its methods does not cause any actions. The advantage of this approach over using an undefined null reference is that the null object is very predictable and has no side effects: it does nothing. It also attempts to eliminate the unpleasant null pointer exception.

Finding it in the JDK

The traditionally mentioned java.base module and the Collection framework, located in the java.util package, define the Collections utility class. This class contains an internal private EmptyIterator class to serve...