Java Interface, AbstractClass and Enum naming convention

Question

We are having this discussion in our team about code conventions for Java for:

• interface: Foo or IFoo or FooInterface?

• abstract: Foo or AbstractFoo?

• Enums: Foo or FooEnum?

I'm basically trying to put my personal preferences aside :) so reasons to back up one or other convention are very welcome.

Answer 1

In Java: Foo, AbstractFoo and Foo - although AbstractFoo could just be Foo.

Evidence:

• java.util.List (interface)
• java.util.AbstractList (abstract class)
• java.util.Formatter.BigDecimalLayoutForm (enum)

For the interface part, see the Naming Conventions section of the Java Coding Conventions document. It doesn't talk about enums and abstract classes though.

Answer 2

From my blog:

• Foo - The interface ultimately defines the concept, so it should have the best name.
• AbstractFoo - An abstract implementation intended to be used as the base of a hierarchy of classes.
• BaseFoo - An implementation intended to be used as the base of a hierarchy of classes, where the base class could be used on its own if necessary.
• DefaultFoo - A "default" implementation that would be appropriate for the majority of typical use cases.
• SimpleFoo - A "simple" implementation with no unexpected functionality, perhaps as an example or as a mock. A simple POJO would be a good "simple" implementation.
• {Descriptive}Foo - Other implementations should describe what makes them unique.

The blog also discusses reasons against some of the other names.