Android Development (II): android Structure

Shows the android project structure:

R. java: The read-only file is automatically generated and defines many constants, which are indexes of all resources of the project. You can use this file to quickly find resources in the project and refresh the new resources when they are added. Define Constants by type, such as string, color, and layout.
AndroidManfest. xml: The android instruction file contains the Actiivity, Service, and explorer used in this project.
Main. xml: Layout file. Layout: setContentView (R. layout. main );
Android applications are constructed by four modules: Activity, Intent, ContentProvider, and Service. However, not every application is composed of these components and can be combined by the openers.
Activity: Represents a screen that a user can see. It is mainly used to process the overall work of an application, such as listening to system events, displaying a specified view for the user, and starting other activities.
Intent:Android uses the special Intent type to implement switching between Activity and Activity.
ContentProvider: Completes data sharing between different android applications. ContentResolver uses the Content Provider you need;
Service: A program with a long life cycle and no user interface, such as a media player that is playing a song from the media playlist.
 
Shows the lifecycle of android:

Uidesign tools: http://code.google.com/p/droiddraw/

 
From Tyrone's column