Java All-in-One For Dummies, 4th Edition

Chapter 5

Creating Generic Collection Classes

Discovering why the generics feature was invented

Using generics in your own classes

Working with wildcards in a generic class

Examining a pair of classes that demonstrate generics

In the previous two chapters, you've seen how you can specify the type for an ArrayList or a LinkedList so the compiler can prevent you from accidentally adding the wrong type of data to the collection. The ArrayList and LinkedList classes can do this because they take advantage of a feature called generics. Generics first became available in Java 1.5.

In this chapter, I show you how the generics feature works and how to put it to use in your own classes. Specifically, you see examples of two classes that use the LinkedList class to implement a specific kind of collection. The first is a stack, a collection in which items are always added to the front of the list and retrieved from the front of the list. The second is a queue, a collection in which items are added to the end of the list and retrieved from the front.

This is one of those chapters where the ...