Sams Teach Yourself Java 2 in 24 Hours

By Rogers Cadenhead

• Table of Contents
  • Copyright
  • About the Author
  • About the Technical Editor
  • Acknowledgments
  • We Want to Hear from You!
  • Reader Services
  • Introduction
  • Hour 1. Becoming a Programmer
  • Hour 2. Writing Your First Program
    • What You Need to Write Programs
    • Creating the Saluton Program
    • Beginning the Program
    • Storing Information in a Variable
    • Saving the Finished Product
    • Compiling the Program into a Class File
    • Fixing Errors
    • Workshop: Running a Java Program
    • Summary
    • Q&A
    • Quiz
    • Activities
  • Hour 3. Vacationing in Java
  • Hour 4. Understanding How Java Programs Work
  • Part II: Learning the Basics of Programming
  • Hour 5. Storing and Changing Information in a Program
  • Hour 6. Using Strings to Communicate
  • Hour 7. Using Conditional Tests to Make Decisions
  • Hour 8. Repeating an Action with Loops
  • Part III: Working with Information in New Ways
  • Hour 9. Storing Information with Arrays
  • Hour 10. Creating Your First Object
  • Hour 11. Describing What Your Object Is Like
  • Hour 12. Making the Most of Existing Objects
  • Part IV: Programming a Graphical User Interface
  • Hour 13. Building a Simple User Interface
  • Hour 14. Laying Out a User Interface
  • Hour 15. Responding to User Input
  • Hour 16. Building a Complex User Interface
  • Part V: Creating Multimedia Programs
  • Hour 17. Creating Interactive Web Programs
  • Hour 18. Handling Errors in a Program
  • Hour 19. Creating a Threaded Program
  • Hour 20. Reading and Writing Files
  • Part VI: Creating Multimedia Programs
  • Hour 21. Using Fonts and Color
  • Hour 22. Playing Sound Files
  • Hour 23. Working with Graphics
  • Hour 24. Creating Animation
  • Part VII: Appendixes
  • Appendix A. Tackling New Features of Java 2 Version 1.4
  • Appendix B. Using the Java 2 Software Development Kit
  • Appendix C. Programming with the Java 2 Software Development Kit
  • Appendix D. Using Sun ONE Studio
  • Appendix E. Where to Go from Here: Java Resources
  • Appendix F. This Book's Web Site

Compiling the Program into a Class File

Before you can try out the program, it must be compiled. The term compile might be unfamiliar to you now, but you will become quite familiar with it in the coming hours. When you compile a program, you take the instructions you have given the computer and convert them into a form the computer can better understand. You also make the program run as efficiently as possible. Java programs must be compiled before you can run them. With the Software Development Kit, programs are compiled using the javac program.

The javac program, like all programs included with the Software Development Kit, is a command-line utility. You run the program by using your keyboard to type a command at a place that can accept the input. This place is what the term command-line refers to.

Because most Linux usage is handled at the command-line, readers with that operating system will be familiar with how the Kit's programs are used. Anyone who used MS-DOS prior to the introduction of Windows has also used a command line.

Many Windows users might not be aware that their operating system includes a command-line feature of its own: the MS-DOS window.

To compile the Saluton program using the Software Development Kit, go to a command-line and open the folder on your system where the Saluton.java file is located, then type the following at the command line:

javac Saluton.java 

If the program compiles successfully, a new file called Saluton.class is created in the same folder as Saluton.java. If you have any error messages, refer to the following section, "Fixing Errors." All Java programs are compiled into class files, which are given the .class file extension. A Java program can be made up of several classes that work together, but in a simple program such as Saluton only one class is needed.

Share This