Private nested Java class in UML diagram

Question

I have a question regarding UML. I have a class which simply contains an inner class with the private access modifier - cannot be accessed from anywhere else... Normally in order to present an inner class relation I can use a (+) relation like here (InnerOddIterator):

(taken from http://www.uml-diagrams.org/nested-classifier.html)

I have not found anywhere any information about how can clearly emphasize that this class is private. Do you know if such a method exist at all? If yes I'll be grateful you give me some link here or something?

Just to keep things clear, a sample code:

public class DataStrucure {
     // fields, methods, etc
     private class InnerOddIterator{
          // ... 
     };
}

Answer 1

From UML point of view. If classifier (Class also) is nested in other class, nesting class plays role of namespace. In this case nested classes are hidden (private) in context namespace. it means, your diagram implicitly defines private inner class definition.

here is part of definition from UML Superstructure section structred classifiers:

"A class acts as the namespace for various kinds of classifiers defined within its scope, including classes. Nesting of classifiers limits the visibility of the classifier to within the scope of the namespace of the containing class and is used for reasons of information hiding. Nested classifiers are used like any other classifier in the containing class."

Answer 2

First of all: You have something in your code and asking for an UML representation. But, IMHO, you should look at it the other way round: How can that UML-idea be represented in code. (Some programming languages don't even offer private nested classes...).

As for private nested classes: I suggest using a Composition. It is stronger as Association but not as strong as inheritance. And the composed class can not exist without its composer. Pretty much exactly a private nested class.

The drawing is taken from http://www.uml-diagrams.org/association.html:

Answer 3

In order to indicate that your inner class is privete the best, for me, is to use - character as depicted below but of course in this case you miss the internal structure of your inner class..