2.4 Jb0115: java oop: first program

Revised: Sun Mar 27 18:57:37 CDT 2016

This Page is included in the following Books:

• Programming Fundamentals with Java
• Object-Oriented Programming (OOP) with Java

Table of contents

• Preface
  • Viewing tip
    • Figures
    • Listings
• Discussion
  • Instructions for compiling and running the program
  • Comments
  • Program output
• Run the program
• Miscellaneous
• Complete program listing

Preface

The purpose of this module is to present the first complete Java program of the collection that previews the most commonforms of the three pillars of procedural programming:

• sequence
• selection
• loop

The program also illustrates

• calling a method,
• passing a parameter to the method, and
• receiving a returned value from the method.

As mentioned above, this is simply a preview. Detailed discussions of these topics will be presented in future modules.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand Listings while you are reading about them.

Figures

• Figure 1 . Program output.

Listings

• Listing 1 . Source code for FirstProgram.

Discussion

Instructions for compiling and running the program

Assuming that the Java Development Kit (JDK) is properly installed on your computer (see Jb0110: Java OOP: Programming Fundamentals, Getting Started ), do the following to compile and run this program.

1. Copy the text from Listing 1 into a text file named FirstProgram.java and store the file in a folder on your disk.

2. Open a command-line window in the folder containing the file.

3. Type the following command at the prompt to compile the program:

4. Type the following command at the prompt to run the program:

Comments

Any text in the program code that begins with // is a comment. The compiler will ignore everything from the // to the end of the line.

Comments were inserted into the program code to explain the code.

The compiler also ignores blank lines.

Note that this program was designed to illustrate the concepts while being as non-cryptic as possible.

Program output

The program should display the text shown in Figure 1 on the screen except that the time will be different each timeyou run the program.

Run the program

I encourage you to copy the code from Listing 1 . Compile the code and execute it. Experiment with the code,making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.

Miscellaneous

This section contains a variety of miscellaneous information.