Through the research for many years, a solution for the problem of extending Java with parametric polymorphism (genericity) has released in Java 5.0. In order to have the capability of backward compatibility and the capability of interoperability with legacy code, Sun adopts the method of type erasure to achieve Java with parametric polymorphism. The method is also called Generalization. Run-time type information will be lost because of type erasure and it’s the major problem of the solution. In the thesis, we show that Java 5.0 can’t declare static variable whose type is type parameter of class due to type erasure and propose a solution for this problem.