试简述由A activity跳转至B activity然后返回到A activity并关闭之的生命周期过程

1. A activity的生命周期:

- onCreate()
- onStart()
- onResume()

2. 从A activity跳转至B activity:

- onPause()
- onStop()

3. B activity的生命周期:

- onCreate()
- onStart()
- onResume()

4. 从B activity返回至A activity:

- onPause()
- onStop()
- onRestart()
- onStart()
- onResume()

5. 关闭A activity:

- onPause()
- onStop()
- onDestroy()