de·caff Java Generics Framework
The de·caff Java Generics Framework (JGF) is a small impact framework which is helping making use of Java generics. Although the framework is quite simple, it brings a bit of functional programming into the Java world. As it is open source you can extract only the parts you like, or use it to learn how things can be done.
It is distributed under an open source ISC license. As usual everything comes without any guarantees.
When to use it
Java is lacking the syntactic support for functional programming, so you'll have to type a lot more than in eg Scala. This means that for one-shots (eg you have a collection and want to do something special to it) a for loop is usually preferable. But if you are using an algorithm more than once making use of the JGF should prove useful, because you have to implement and take care of the algorithm only in one place.