(This book is the latest revision of the Andorid Platform Development Journey [1] published in 2010. It covers the new features of Android 3/4, and the development cases of security practice, and introduces the basic concept, practical technology and use mode of Android platform development. The primary contents include the use of program framework, high-end interface, database use, network communication and Web development, wireless communication, multimedia use, personal information management, telephone system management, XML use, map use and system information management. This book selects 95 cases, of which 70 are based on Android 2.2.1 and 2.3.5 real machine development, and 25 are based on Android 3. x simulator. This book is mainly aimed at developers with certain mobile platform development experience, as well as programmers who are interested in Android platform development. This document includes the following annexes:)