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
    • Scroll Panes
    • Sliders
    • Change Listeners
    • Menus
    • Workshop: Using Image Icons and Toolbars
    • Summary
    • Q&A
    • Quiz
    • Questions
    • Activities
  • 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

Sliders

One of the easiest ways for a user to enter numeric input is by using a slider, a component that can be dragged from side to side or up and down.

Sliders are represented in Swing by the JSlider class. Figure 16.2 shows what a slider component looks like.

Figure 16.2 Displaying a slider component.

Sliders enable a number to be chosen from between a minimum and maximum range of values. These values can be displayed on a label that includes the minimum value, maximum value, and intermediate values (as shown later in Figure 16.3).

Figure 16.3 Choosing a color using slider components.

You can create a horizontal slider with one of the following constructors:

• JSlider( int , int )— Create a slider with the specified minimum value and maximum value.
• JSlider( int , int , int )— Create a slider with the specified minimum value, maximum value, and starting value.

To create a vertical slider, you must use a constructor method with an additional argument—the orientation of the slider. This argument should be the class variables JSlider.VERTICAL or JSlider.HORIZONTAL.

The following statement creates a vertical slider that can be used to pick a number from 1 to 1,000:

JSlider guess = new JSlider(JSlider.VERTICAL, 1, 1000, 500); 

This slider starts with the caret—the part of the component used to select a number—at the 500 position.

To display a label for a slider, you must set up the information that the label will contain. Call the slider's setMajorTickSpacing( int ) and setMinorTickSpacing( int ) methods to determine how often a tick mark will be displayed on the label. Major ticks are displayed as a thicker line than minor ticks.

After you have set up how often tick marks will appear, call the slider's setPaintTicks( boolean ) method with true as the argument.

You can also display the numeric value of each major tick by calling the slider's

setPaintLabels( boolean ) method with true.

The following statements can be used to create the slider shown in Figure 16.2:

JSlider percentage = new JSlider(0, 100, 25); 
percentage.setMajorTickSpacing(10); 
percentage.setMinorTickSpacing(5); 
percentage.setPaintTicks(true); 
percentage.setPaintLabels(true); 

Share This