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
  • 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
    • Creating Arrays
    • Using Arrays
    • Multidimensional Arrays
    • Sorting an Array
    • Workshop: Array of Prizes, Indeed
    • Summary
    • Q&A
    • Quiz
    • Activities
  • 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

Hour 9. Storing Information with Arrays

No one benefited more from the development of the computer than Santa Claus. For centuries, humankind has put an immense burden on him to gather and process information. Old St. Nick has to keep track of the following things:

• Naughty children
• Nice children
• Gift requests
• Homes with impassable chimneys
• Women who want more from Santa than Mrs. Claus is willing to let him give
• Countries that shoot unidentified aircraft first and ask questions later

Computers were a great boon at the North Pole. They are ideal for the storage, categorization, and study of information.

The most basic way that information is stored in a computer program is by putting it into a variable. However, this method is limited to relatively simple usage. If Santa had to give each naughty child his or her own variable name, he'd be working on the program for the next 12 holiday seasons at least, to say nothing of the effect on his jolly disposition.

The list of naughty children is an example of a collection of similar information. Each child's name is a string of text or some kind of Santa Information System ID number. To keep track of a list of this kind, you can use arrays.

Arrays are groups of related variables that share the same type. You can have arrays of any type of information that can be stored as a variable. Arrays can be used to keep track of more sophisticated types of information than a single variable, but they are almost as easy to create and manipulate as variables.

The following topics will be covered during this hour:

• Creating an array
• What a dimension of an array is
• Giving a value to an array element
• Changing the information in an array
• Making multidimensional arrays
• Sorting an array

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