Chapter 10: Using Arrays and Collections

Chapter 10

Using Arrays and Collections

After completing this chapter, you will be able to:

• Declare, initialize, copy, and use array variables.

• Declare, initialize, copy, and use variables of various collection types.

So far, you have seen how to create and use variables of many different types. However, all the examples of variables you have seen so far have one thing in common—they hold information about a single item (an int, a float, a Circle, a Time, and so on). What happens if you need to manipulate sets of items? One solution would be to create a variable for each item in the set, but this leads to a number of further questions: How many variables do you need? How should you name them? If you need to perform the same operation on each item in the set (such as increment each variable in a set of integers), how would you avoid very repetitive code? This solution assumes that you know, when you write the program, how many items you will need, but how often is this the case? For example, if you are writing an application that reads and processes records from a database, how many records are in the database, and how likely is this number to change?

Arrays and collections provide mechanisms that help to solve the problems posed by these questions.