Introduction

Welcome to the wonderful world of Android. A world where, with a bit of knowledge and effort, you too can write Android applications. To write good applications, however, you will need to dig deeper, to understand the fundamentals of the Android architecture, to understand how applications can work together, to understand how mobile applications are different from all previous forms of programming. The online documentation on Android is fair, but it does not go far enough. You can read the source code, but that's not at all easy.

This book is the culmination of seven years of researching, developing, testing, refining, and writing about Android. We've read all the online documentation, scoured through source code, explored the far reaches of the Internet, and have compiled this book. We've filled in the gaps, anticipated the questions you have, and provided answers. Along the way we've seen APIs come and go and be revised. We've seen major changes in how applications are constructed. At first we all used Activities, but when tablets came along we started using Fragments. We've taken everything we've learned and filled this book with practical guidance to using the latest Android APIs to write interesting applications.

You will still find coverage of the beginning topics, to help the new learner get started developing for Android. You will also find coverage of the more advanced topics, such as Google Maps Android API v2, which is very different from v1. We've updated this edition with the latest information on the available APIs. You will find in-depth coverage of intents, services, broadcast receivers, communication, fragments, widgets, sensors, animation, security, Google Cloud Messaging, audio and video, and more. And for every topic there are sample programs that illustrate each API in meaningful ways. All source code is downloadable, so you can copy and paste it into your applications to get a great head start.