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
    • for Loops
    • while Loops
    • do-while Loops
    • Exiting a Loop
    • Naming a Loop
    • Workshop: Teaching Your Computer a Lesson
    • Summary
    • Q&A
    • Quiz
    • Activities
  • 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

Exiting a Loop

The normal way to exit a loop is for the condition that is tested to become false. This is true of all three types of loops in Java: for, while, and do-while. However, there might be times when you want a loop to end immediately, even if the condition being tested is still true. You can do this with a break statement, as shown in the following code:

int index = 0; 
while (index <= 1000) { 
    index = index + 5; 
    if (index == 400) 
        break; 
    System.out.println("The index is " + index); 
} 

The condition tested in the while loop sets it up to loop until the value of the index variable is greater than 1,000. However, a special case causes the loop to end earlier than that: If index equals 400, the break statement is executed, ending the loop immediately.

Another special-circumstance statement you can use inside a loop is continue. The continue statement causes the loop to exit its current trip through the loop and start over at the first statement of the loop. Consider the following loop:

int index = 0; 
while (index <= 1000) { 
    index = index + 5; 
    if (index == 400) 
        continue; 
    System.out.println("The index is " + index); 
} 

In this loop, the statements will be handled normally unless the value of index equals 400. In that case, the continue statement causes the loop to go back to the while statement instead of proceeding normally to the System.out.println() statement. Because of the continue statement, the loop will never display the following text:

The index is 400 

You can use the break and continue statements with all three kinds of Java loop statements.

Share This