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

TreeField


A TreeField is a relatively new field released with version 4.5 of the SDK, and a close cousin to the ListField. The TreeField does not inherit from the ListField so they aren't directly related, but I would wager that the implementation of the TreeField borrows very heavily from the ListField. As the name implies, a TreeField is used to display information which is organized into a hierarchical format, also called a tree, and can show a parent-child type of relationship in the data.

A tree always starts with a root node, which is to say a node with no parent. That root node then has child nodes, each of which can have their own child nodes and so on. This growth of nodes from a single root is much like how a tree will grow with branches that in turn have their own smaller branches. At the end of the branches are leaves, which in a TreeField are nodes with no child nodes of their own.

Hierarchical data, like that of a file system, is best shown using a TreeField. In the TreeField...