Android Activity Life Cycle

environment: run on froyo emulator
[launch app] --> onCreate() --> onStart() --> onResume()

[screen lock] --> onPause(), and then [screen unlock] --> onResume()

[home | dial]  --> onPause() --> onStop(),
  and then [launch app again | back] --> onRestart() --> onStart() --> onResume()

[back]  --> onPause() --> onStop() --> onDestroy()