Nullable type

In programming languages like C# 2.0, a nullable integer, for example, can be declared by a question mark (int?

Its values can be either "true" or "false", while a nullable Boolean may also contain a representation for "undecided".

However, the interpretation or treatment of a logical operation involving such a variable depends on the language.

Java has classes that correspond to scalar values, such as Integer, Boolean, and Float.

[citation needed] Nullable type implementations usually adhere to the null object pattern.