Java Practices->Avoid null if possible

Avoid null if possible

Some argue that allowing null into the API of a class, in the form of possibly-null parameters or return values, should be avoided if possible:

null references can only be used in a boolean test - any other use will throw a NullPointerException
null references always represent special cases, and if these special cases can be removed, the code will be easier to understand
null return values are error prone, since there is no way to ensure that the caller always does a check-for-null.
methods which accept an explicit null reference as a valid argument are less intelligible at the point of call. The reader will usually need to consult documentation to determine what exactly the null argument means. (Instead of passing a null literal, it's usually more helpful to the reader to pass a well-named null object variable instead.)

If null is allowed for a method, then this should be clearly stated in its javadoc. Some follow the convention that all items are assumed to be non-null unless otherwise specified. Such a convention could be explicitly stated once in the javadoc overview.html.

There's a very common exception to this rule. For Model Objects, which map roughly to database records, it's often appropriate to use null to represent optional fields stored as NULL in the database.

The Objects class has null-friendly methods designed to help you work with null objects.