Core Java for the Impatient, 3rd Edition

Chapter 6

Generic Programming

Topics in This Chapter

• 6.1 Generic Classes

• 6.2 Generic Methods

• 6.3 Type Bounds

• 6.4 Type Variance and Wildcards

• 6.5 Generics in the Java Virtual Machine

• 6.6 Restrictions on Generics

• 6.7 Reflection and Generics

• Exercises

You often need to implement classes and methods that work with multiple types. For example, an ArrayList<T> stores elements of an arbitrary class T. We say that the ArrayList class is generic, and T is a type parameter. The basic idea is very simple and incredibly useful. The first two sections of this chapter cover the simple part.

In any programming language with generic types, the details get tricky when you restrict or vary type parameters. For example, suppose you want to sort elements. Then ...