Are there any standard generic "callback" or "function/method" types in Java, like System.Action<T> or System.Func<T,U> in .NET?
In my concrete case, I need a class that wraps a method that takes one (generic) parameter of type T and returns nothing (i.e. void).
Yes, it's easy enough to create such a class/interface for myself, but I'd prefer a standard library class if there is one.
I don't believe there's anything in the standard library like this, no (at the time of writing, 2010). Other libraries have them - things like Guice's Provider<T> and Guava's Function<F, T>, Supplier<T> and Predicate<T>... so if you're using libraries already, you might want to look into what they provide in this direction.
(EDIT: As noted, those are interfaces which return things - so similar to Func<T, U> but not similar to Action<T>.)