(This e-book is themed on the practical use of android mobile phones. The whole book is basically composed of typical mobile phone programs, involving user interface (UI), layout, widget controls, communication services, mobile phone hardware control, mobile phone operating system services, telephone services, multimedia playback and use, the Internet, Google API, GPS positioning, Google Maps, ORCode (two-dimensional barcode), etc. Have a certain knowledge of Java programming language, have the ability to identify and troubleshoot basic program logic, be interested in Android development, or be an engineer studying Android development, etc. It is suggested to learn this book after laying a good foundation in Java if you have no knowledge of program language. This document includes the following annexes:)