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
    • Testing a Condition
    • if Statements
    • if-else Statements
    • switch Statements
    • The Conditional Operator
    • Workshop: Watching the Clock
    • Summary
    • Q&A
    • Quiz
    • Activities
  • 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

if-else Statements

There are times when you want to do something if a condition is true and do something else if the condition is false. You can do this by using the else statement in addition to the if statement, as in the following example:

if (answer == correctAnswer) { 
    score += 10; 
    System.out.println("That's right. You get 10 points."); 
} 
else { 
    score -= 5; 
    System.out.println("Sorry, that's wrong. You lose 5 points."); 
} 

The else statement does not have a condition listed alongside it, unlike the if statement. Generally, the else statement is matched with the if statement that immediately comes before it in a Java program. You also can use else to chain several if statements together, as in the following example:

if (grade == 'A') 
    System.out.println("You got an A. Great job!"); 
else if (grade == 'B') 
    System.out.println("You got a B. Good work!"); 
else if (grade == 'C') 
    System.out.println("You got a C. You'll never get into a good " 
        + "college!"); 
else 
    System.out.println("You got an F. You'll do well in Congress!"); 

By putting together several different if and else statements in this way, you can handle a variety of conditions. In the preceding example, a specific message is sent to A students, B students, C students, and future legislators.

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