Learing note:andriod app

awareing a few directories and files in a android project:

(https://developer.android.com/training/basics/firstapp/running-app.html)

files:
AndroidManifest.xml
a manifest file, it describes  
1) fundamental characteristicsof the app
2) defines each of app's components

directories:
src/
app's main source file, including an activity class that runs when your app is launched

res/
app resources
contains several sub-directories
   drawable-hdpi/
 layout/
 values/
  ...