Advanced Type Systems for Java in Real-World Programs

I show that a high ratio of type-casts can be removed from a typical Java project by applying dierent type-system exten- sions. Especially the f-bounded parametric polymorphism and covariant return-types (both included in the upcoming Java 1.5 release) can be applied very successfully, but there remain typing-problems that can be better solved using dif- ferent approaches.