Job Ready Java

Lesson 22Introduction to Lists

This lesson is a quick introduction to Lists. Lists are a type of data structure that allows you to store values and objects in a more flexible manner than arrays.

LEARNING OBJECTIVES

By the end of this lesson, you will able to:

• Describe some of the different types of Lists available
• Explain how generic types work in Java
• Use Lists in your code
• Use enhanced for loops with Lists
• Create and use an Iterator

LIST

List is an interface that extends Collection. It is an ordered collection of items that may include duplicate elements. The List interface has quite a few methods, but the ones that you will be using most are the following:

• add
• get
• remove
• size

We include examples of using these methods in this lesson, but you should read the Javadoc associated with these methods to become familiar with how they work.

TYPES OF LISTS

There are several types of Lists that exist in the Java Collections Framework. Although we will focus on the ArrayList, we will also discuss the LinkedList and Stack so that you are prepared if a situation arises where your program can benefit from them. In addition to the ArrayList, let's take a quick look at the LinkedList and Stack.

ArrayList

Think of the ArrayList class as a supercharged array. Arrays are great data structures, but they have some limitations, especially that once defined, Arrays cannot shrink or grow. An ArrayList can automatically shrink and grow dynamically, so you can easily add or remove ...