Book Image

BlackBerry Java Application Development

Book Image

BlackBerry Java Application Development

Overview of this book

BlackBerry Smartphone was once the domain of jet-setting business users with power suits. Now you can hardly go anywhere without seeing someone using a BlackBerry to check their messages or make a call. It's this kind of explosive growth that makes the BlackBerry ecosystem a great place to develop and market applications through the BlackBerry App World store—this book shows you how to do just that! This step-by-step guide gives you a hands-on experience of developing innovative Java applications for your BlackBerry. With the help of this book, you will learn to build your own applications to illustrate the platform, and the various capabilities that developers can use in their programs. It explores the powers of Blackberry and helps you develop professional and impressive Java applications. The book teaches how to write rich, interactive, and smart BlackBerry applications in Java. It expects the readers to know Java but not Java Mobile or the BlackBerry APIs. We will learn to build rich, interactive, and smart Java applications for the BlackBerry. The book will cover UI programming, data storage, programming network, and internet API apps. As we move on, we will learn more about the BlackBerry's device features, such as messaging, GPS, multimedia, contacts and calendar, and so on.This book also helps you build your own applications to illustrate the platform, and the various capabilities that developers can use in their programs.
Table of Contents (18 chapters)
BlackBerry Java Application Development
Credits
About the Author
Acknowledgement
About the Reviewers
Preface

ChoiceField


The ChoiceField is an abstract base class that is analogous to a drop list or pick list on other platforms. You can't use a ChoiceField directly, instead you must use one of the two specialty-derived classes—the NumericChoiceField or the ObjectChoiceField. These classes have common functionality though, which we can outline here.

Using a ChoiceField type of field allows the user to choose a specific value from a short list of predetermined values. Initially, the ChoiceField is collapsed and shows only the selected value.

When you click the trackball while the field is selected a small dialog opens up to display the full list of possible choices. The user can scroll up and down in the list and click the trackball to select a value.

A ChoiceField type of class is typically used when there is a small and fixed list of possible choices that does not lend itself to the user entering free-form text. As a designer, you have to make sure that the complete list is represented because the...