【Android入门】Android project files

AndroidManifest.xml

The manifest file describes the fundamental characteristics of the app and defines each of its components. 

One of the most important elements your manifest should include is the <uses-sdk> element. This declares your app's compatibility with different Android versions using the android:minSdkVersion andandroid:targetSdkVersion attributes. For your first app, it should look like this:

<manifest xmlns:android="http://schemas.android.com/apk/res/android" ... >    <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17" />    ...</manifest>

You should always set the android:targetSdkVersion as high as possible and test your app on the corresponding platform version.

src/

Directory for your app's main source files. By default, it includes an Activity class that runs when your app is launched using the app icon.

res/

Contains several sub-directories for app resources. Here are just a few:

drawable-hdpi/

Directory for drawable objects (such as bitmaps) that are designed for high-density (hdpi) screens. Other drawable directories contain assets designed for other screen densities.

layout/

Directory for files that define your app's user interface.

values/

Directory for other various XML files that contain a collection of resources, such as string and color definitions.

When you build and run the default Android app, the default Activity class starts and loads a layout file that says "Hello World." The result is nothing exciting, but it's important that you understand how to run your app before you start developing.