1.Android 四大天王:Activity(程序的界面),Intent(数据传输),Service(服务),Content Provider(数据存放)

2.产生APK安装包:Android Manifest里的Export

3.Activity的生命周期:onCreate->onStart->onResume->onPause->Other Activity’s onCreate,onStart,onResume-> onStop()(完全不可见后,才会调用,如第二个ACtivity是Dialog,则不发生),再按Back后,Other Activity’s onPause ->First Activity’s onStart->onResume, Other Activity’s onStop() , onDestroy()(再起来时一定要再有onCreate)

4. A task is a stack of Activities.