this is a "hello world" sample.
Hello, I'm a android developper. I'm better at android system develop than android app. I know AMS, IMS, PMS and also android system service, JNI, AIDL, native service, and can support java/c++ Api. I know app develop, but It is only preinstall app, such as MediaPlayer, Settings, Music, Gallery... for 3th open source Android library, I know less. So I need to study about these.