片段/活动生命周期和方向变化

Question

片段是有趣的东西,但是,我想,一旦你知道它们的怪癖,它们就是在多个设备上编写优秀代码的宝贵工具.

然而,在修复方向改变错误时,我碰到了墙.为了让我的片段能够工作,它需要访问属于它的View,它包含Activity,引导我进行快乐的追逐,试图找到Activity和Fragment生命周期的交互方式.

我在其onCreate()方法中将一个片段添加到我的"活动"视图中:

// Only add a fragment once, as after it's been added it cannot be replaced (Even though there is a .replace() method. Which is a massive gaping hole in fragments as a technology if you ask me)
if(savedInstanceState == null) {
    MainMenuFragment menu= new MainMenuFragment();
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();   
    transaction.replace(R.id.menuFrame, menu);  
    transaction.commit();
}

通往此活动 - >片段生命周期:

01-04 15:17:27.226: W/SinglePaneActivity 0:   onCreate()
01-04 15:17:27.378: W/MainMenuFragment   0:   onAttach() to SinglePaneActivity 0
01-04 15:17:27.378: W/MainMenuFragment   0:   onCreate()
01-04 15:17:27.453: W/MainMenuFragment   0:   onActivityCreated()
01-04 15:17:27.476: W/MainMenuFragment   0:   onStart()
01-04 15:17:27.476: W/SinglePaneActivity 0:   onStart()
01-04 15:17:27.476: W/SinglePaneActivity 0:   onResume()
01-04 15:17:27.476: W/MainMenuFragment   0:   onResume()

然而,方向更改突出显示通常不是这种情况,片段onCreate()方法在其父活动之后不会被调用onCreate().事实上,Fragment的第一个生命周期调用onAttach()发生在甚至创建Activity之前(null作为参数传递):

01-04 15:10:49.589: W/MainMenuFragment   0:   onPause()
01-04 15:10:49.589: W/SinglePaneActivity 0:   onPause()
01-04 15:10:49.589: W/MainMenuFragment   0:   onStop()
01-04 15:10:49.589: W/SinglePaneActivity 0:   onStop()
01-04 15:10:49.589: W/MainMenuFragment   0:   onDestroyView()
01-04 15:10:49.589: W/MainMenuFragment   0:   onDestroy()
01-04 15:10:49.589: W/MainMenuFragment   0:   onDetach()
01-04 15:10:49.609: W/SinglePaneActivity 0:   onDestroy()
01-04 15:10:49.617: W/MainMenuFragment   1:   onAttach() to null
01-04 15:10:49.617: W/MainMenuFragment   1:   onCreate()
01-04 15:10:49.617: W/SinglePaneActivity 1:   onCreate()
01-04 15:10:49.890: W/MainMenuFragment   1:   onActivityCreated()
01-04 15:10:49.917: W/MainMenuFragment   1:   onStart()
01-04 15:10:49.917: W/SinglePaneActivity 1:   onStart()
01-04 15:10:49.921: W/SinglePaneActivity 1:   onResume()
01-04 15:10:49.921: W/MainMenuFragment   1:   onResume()

我完全不知道为什么会这样.任何人都可以解释为什么Fragment.onAttach()在它包含Activity之前被调用了吗？

我得到的片段不需要访问其包含的活动(直到UI交互)按预期工作.

Answer 1

哎呀,

01-04 15:46:23.175: W/MainMenuFragment   0: onAttach() to SinglePaneActivity 0
01-04 15:46:23.179: W/MainMenuFragment   0: onCreate()
01-04 15:46:23.246: W/MainMenuFragment   0: onActivityCreated() with Activity SinglePaneActivity 0
01-04 15:46:23.269: W/MainMenuFragment   0: onStart()
01-04 15:46:23.269: W/SinglePaneActivity 0: onStart()

为什么那里有onAttach()一种我不知道的方法.特别是因为"附加"发生在有活动之前.

我需要的方法当然是onActivityCreated()作为Fragment生命周期事件的"Creation"集中的最终调用.