Activity生命周期

onCreate()->Created->onStart()->Started(visible)->onResume()->Resumed(visible)

->onPause()->Paused(partially visible)->onStop()->Stopped(hidden)->onDestroy()->Destroyed

Paused Activity通过onResume()，Stopped Activity通过onReStart()->onStart()

特殊场景

屏幕旋转时的Activity

Activity运行中--屏幕旋转-->onPause()->onStop()->onDestroy()->onCreate()->onStart()->onResume()->Activity运行中

低内存恶劣环境

Activity运行中-home键->onPause()->onStop()-低内存->onDestroy()->Activity killed