Introduction

This chapter introduces the important topic of data structurescollections of related data items. Arrays are data structures consisting of related data items of the same type. Arrays are fixed-length entitiesthey remain the same length once they are created, although an array variable may be reassigned such that it refers to a new array of a different length.

After discussing how arrays are declared, created and initialized, this chapter presents a series of practical examples that demonstrate several common array manipulations. We also present a case study that examines how arrays can help simulate the shuffling and dealing of playing cards for use in an application that implements a card game. The chapter then introduces Java's enhanced for statement, which allows a program to access the data in an array more easily than the counter-controlled for statement presented in Section 5.3 does. Two sections of the chapter enhance the case study of class GradeBook in Chapters 35. In particular, we use arrays to enable the class to maintain a set of grades in memory and analyze student grades from multiple exams in a semestertwo capabilities that were absent from previous versions of the class. These and other chapter examples demonstrate the ways in which arrays allow programmers to organize and manipulate data.