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
  • 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
    • Threads
    • Working with Threads
    • Starting with init()
    • Catching Errors as You Set Up URLs
    • Handling Screen Updates in the paint() Method
    • Starting the Thread
    • Handling Mouse Clicks
    • Workshop: Revolving Links
    • Summary
    • Q&A
    • Quiz
    • Questions
    • Activities
  • 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

Starting with init()

The init() method of an applet automatically is handled once when the applet first starts to run. In this example, this method is used to assign values to the two arrays created for this applet, pageTitle and pageLink. It also is used to create a clickable button that will appear on the applet. The method consists of the following statements:

public void init() { 
    pageTitle[0] = "Sun's Java site"; 
    pageLink[0] = getURL("http://java.sun.com"); 
    pageTitle[1] = "Cafe au Lait"; 
    pageLink[1] = getURL("http://www.ibiblio.org/javafaq/"); 
    pageTitle[2] = "JavaWorld"; 
    pageLink[2] = getURL("http://www.javaworld.com"); 
    pageTitle[3] = "Java 2 in 24 Hours"; 
    pageLink[3] = getURL("http://www.java24hours.com"); 
    pageTitle[4] = "Sams Publishing"; 
    pageLink[4] = getURL("http://www.samspublishing.com"); 
    pageTitle[5] = "Workbench"; 
    pageLink[5] = getURL("http://workbench.cadenhead.info"); 
    Button goButton = new Button("Go"); 
    goButton.addActionListener(this); 
    FlowLayout flow = new FlowLayout(); 
    Container pane = getContentPane(); 
    pane.setLayout(flow); 
    pane.add(goButton); 
    setContentPane(pane); 
} 

Strings are assigned to the six elements of the pageTitle array, which stores the title of each Web page. The elements of the pageLink array are assigned a value returned by the getURL() method, which you will be creating for this program.

The last seven statements of the init() method are used to create a button and place it on the applet window. The button has the name goButton and is labeled with the text Go.

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