Job Ready Java

Lesson 13Organizing with Arrays

Arrays are the first collection type that we are going to learn about. It is the most fundamental of the collection types, and many of the other collection types we will learn later use the array structure under the covers in creative ways to yield interesting effects.

When we mention that a type is a collection, we mean that it can hold multiple simple or complex data values inside it.

LEARNING OBJECTIVES

By the time you finish this lesson, you will be able to:

• Differentiate between elements of an array and the indexes of those elements
• Explain one-dimensional, multidimensional (including two-dimensional), and jagged arrays
• Instantiate different ranks and lengths of arrays
• Access elements in an array
• Deal with errors that occur when attempting to access an array

WHAT IS AN ARRAY?

We have covered a lot of Java basics up to this point. We understand variable types, and we can use flow of control statements to branch and loop our code blocks. We also learned how to group repeatable blocks of code into methods. The next piece we need to understand is how to store and work with collections of items.

Consider a situation where we want to store a list of five integers. Without collections like arrays, we would have to declare five variables. That's maybe not a big deal when we are talking about five variables, but what if you had to store 10,000 variables? This is where arrays help us.

An array is a set of uniform data elements that can ...