This chapter explores the key elements that we use in a program: objects and primitive data. We develop the ability to create and use objects for the services they provide. This ability is fundamental to the process of writing any program in an object-oriented language such as Java. We use objects to manipulate character strings, obtain information from the user, perform complex calculations, and format output. In the Graphics Track of this chapter, we explore the relationship between Java and the Web, and delve into Java’s abilities to manipulate color and draw shapes.

chapter objectives

Establish the difference between primitive data and objects.
Declare and use variables.
Perform mathematical computations.
Create objects and use them for the services they provide.
Explore the difference between a Java application and a Java applet.
Create graphical programs that draw shapes.