Introduction Notice: This tutorial is a work in progress. Stay tuned for further refinements.This tutorial describes an experimental extension of the Java programming lan-guage, known as variance, that adds to the generics features proposed in JSR-014. At the time of this writing, the features described here are under considerationby the JSR-014 expert group. The paper introduces the concepts of variant generic classes and statically safe arrays, in terms of read-only and write-only classes. It briefly explainsgeneric classes in general, but otherwise assumes familiarity with GJ. In the first part, read-only generic classes are introduced. Then, before the other kinds of variance on classes are described, read-only, invariant and write-only arrays are described. Then write-only and bivariant generic classes areintroduced.