Activity和Fragment生命周期变化

情形一:启动应用加载Activity和Fragment

Activity::onCreate

Fragment::onAttach

Fragment::onCreate

Fragment::onCreateView

Fragment::onActivityCreate

Activity::onStart

Fragment::onSatrt

Activity::onResume

Fragment::onResume

情形二:fragA->fragB->fragA(Fragment不加入回退栈)

销毁FragmentA：

启动FragmentB:

销毁FragmentB:

启动FragmentA:

启动过程如下

onAttach

onCreate

onCreateView

onActivityCreate

onSatrt

onResume

销毁过程如下:

onPause

onStop

onDestroyView

onDestroy

onDetach

在不加入回退栈的情况下,无论多少Fragment之间的切换，都遵循启动下一个，销毁上一个的原则,在屏幕不旋转的情况下Activity是不会发生任何变化的

情形三:旋转Fragment(与加不加入回退栈没关系,过程都一样)

Activity和Fragment都会被销毁,其中销毁过程Fragment会保存状态

Fragment::onPause
Activity::onPause
Fragment::onSaveInstanceState(保存销毁前的状态)
Fragment::onStop
Activity onStop
Fragment::onDestroyView
Fragment::onDestroy
Fragment::onDetach
Activity::onDestroy

创建Activity和Fragment(与一开始启动应用过程相同)
Activity::onCreate
Fragment::onAttach
Fragment::onCreate
Fragment::onCreateView
Fragment::onActivityCreated
Fragment::onAttach
Fragment::onCreate
Fragment::onCreateView
Fragment::onActivityCreated

Activity onStart
Fragment::onStart
Fragment::onStart

Activity::onResume
Fragment::onResume
Fragment::onResume

情形四:FragmentA->FragmentB->FragmentA(两者都加入回退栈)

停止FragmentA,但是不销毁,与不加入回退栈相比唯一的不同就是不会被销毁

FragmentA::onPause
FragmentA::onStop
FragmentA::onDestroyView

启动FragmentB

"恢复"FragmentA,这种恢复会从Fragment的onCreateView开始,重新绘制页面,所以之前的所有数据都已经不在了，这就涉及到Fragment的状态保存(下节待续)

onCreateView
onActivityCreated
onStart
onResume