Android Learning first day (Introduction and Basics of Android):

(1):Android architecture;

Application layer (applications), Application framework layer (application framework), System Runtime Layer (librarries), Linux kernel layer (Linux Kernel);

(2) the role of folders in Android projects:

NO.	Folder	Describe
1	Src	Store all. Java source files
2	Gen	Save the path for the automatically generated code file for the ADT plug-in, where the R.java file will save all resource IDs
3	Assets	Can store some of the larger resource files in the project (slices, music, fonts, etc.)
4	Res	Can be stored in the project so resource files, slices, nets, text
5	res\drawable-hdpi	Save high-resolution picture resources
6	res\drawable-idpi	Save low-resolution picture resources
7	res\drawable-mdpi	Save in resolution picture resource
9	Res\layout	The layout file is stored so that it is used to arrange different display components.
9	Res\values	Information for storing some resource files, for reading text resources, there are some agreed file names in this folder Arrays.xml: Defining Array Data Colors.xml: Defines the data that represents the color dimens.xml: Define a scale that can be used toobtain these resources using the Resources.getdimension () method String.xml: Defines a string that can be used with resources.getstring () obtained Resources.gettext () method to obtain these resources Styles.xml: Defines the displayed style file
10	Res\raw	customization of some native files in the directory, such as music, video file format, can be used Resources.getrawresource () method to obtain these resources
11	Res\xml	user-defined XML file, all files are compiled into the application when the program is run, Resources.getxml () can be used while the program is running Method gets
12	Res\anim	Used to define an animated object

(3) the role of files in Android projects:

NO.	File	Describe
1	Hello.java	As the activity program, similar to the main class in a Java program
2	Icon.png	The picture resource files required in the project, in Drawable-hdpi, drawable-idpi, drawable-mdpi folder to save images in different resolutions
3	Main.xml	To configure all controls
4	Strings.xml	To configure all resource information
5	R.java	This file is a system file that is automatically generated and maintained
6	Androidmanifest.xml	The main configuration file for Android, which configures individual components or some access rights, etc.
7	Default.properties	Properties definition file for Android project

Android Learning first day (Introduction and Basics of Android):