Introduction

We now introduce Java application programming which facilitates a disciplined approach to program design. Most of the Java programs you will study in this book process information and display results. We present six examples that demonstrate how your programs can display messages and how they can obtain information from the user for processing. We begin with several examples that simply display messages on the screen. We then demonstrate a program that obtains two numbers from a user, calculates their sum and displays the result. You will learn how to perform various arithmetic calculations and save their results for later use. Many programs contain logic that requires the program to make decisions. The last example in this chapter demonstrates decision-making fundamentals by showing you how to compare numbers then display messages based on the comparison results. For example, the program displays a message indicating that two numbers are equal only if they have the same value. We analyze each example one line at a time to help you ease your way into Java programming. To help you apply the skills you learn here, we provide many fun and challenging problems in the chapter's exercises.