The concept of a data structure (e.g., a stack) that contains data elements can be understood independently of the element type it manipulates. A generic class provides a means for describing a class in a type-independent manner. We can then instantiate type-specific versions of the generic class. This capability is an opportunity for software reusability.
With a generic class, you can use a simple, concise notation to indicate the actual type(s) that should be used in place of the class’s type parameter(s). At compilation time, the compiler ensures your code’s type safety, and the runtime system replaces type parameters with type arguments to enable your client code to interact with the generic class.