Android (Child)FragmentManager 正确使用子子片段
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Proper use of sub sub fragments with (Child)FragmentManager
提问by prom85
How do I properly use Fragments in Fragments?
如何在 Fragments 中正确使用 Fragments？
My (simplified) use case is following, I have an activity with a layout fragment and this fragment theirself contains a sub fragment... all fragments are added manually to their parents...
我的（简化的）用例如下，我有一个带有布局片段的活动，这个片段本身包含一个子片段......所有片段都手动添加到他们的父母......
----------------------------------------------------------
- Activity -
- -
- -
- --------------------------------------- -
- - Fragment - -
- - - -
- - ----------------- - -
- - - SubFragment - - -
- - - - - -
- - - - - -
- - ----------------- - -
- --------------------------------------- -
- -
----------------------------------------------------------
Now in my activity's onCreateI do following:
现在在我的活动中，onCreate我执行以下操作：
if (savedInstanceState == null)
{
// I create the fragment
mMainFragment = new MainFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_main, mMainFragment);
transaction.commit();
}
else
{
// I retrieve the fragment
mMainFragment = (BaseFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_main);
}
And in my fragments onCreateI get/create my SubFragment:
在我的片段中，onCreate我得到/创建了我的子片段：
mSubFragment = getChildFragmentManager().findFragmentByTag(SubFragment.class.getName());
if (mSubFragment == null)
{
mSubFragment = new SubFragment();
getChildFragmentManager().beginTransaction().add(R.id.fragment_sub, mSubFragment, SubFragment.class.getName()).commit();
}
Problem
问题
After screen rotation, my SubFragment is added twice... If I use the activity's FragmentManagerthen it works... But why does it not work with the ChildFragmentManager? Of course, the Fragment is a new fragment, but the activity is a new one as well, so why does it work with the activity's FragmentManagerbut not with the parent fragment's one?
屏幕旋转后，我的 SubFragment 被添加了两次......如果我使用该活动，FragmentManager那么它就可以工作......但为什么它不能与ChildFragmentManager? 当然，Fragment 是一个新的 Fragment，但 Activity 也是一个新的 Fragment，那么为什么它可以与 Activity 一起工作，FragmentManager而不能与父Fragment 一起工作呢？
In a fragment, I should use the fragments ChildFragmentManager, shouldn't I?
在片段中，我应该使用片段ChildFragmentManager，不是吗？
回答by ashakirov
You should add SubFragmentto Fragmentthe same way like you add Fragmentto Activity. I mean adding Fragmentto Activityshould look like:
您应该添加SubFragment到Fragment像你添加相同的方式Fragment来Activity。我的意思是添加Fragment到Activity应该看起来像：
@Override
public void onCreate(Bundle savedInstanceState) {
....
if (savedInstanceState == null){
//add fragment
mMainFragment = new MainFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_main, mMainFragment);
transaction.commit();
}
}
Adding SubFragmentto MainFragmentshould look like:
添加SubFragment到MainFragment应如下所示：
public class MainFragment extends Fragment{
@Override
public View onCreateView(LayoutInflater i, ViewGroup c, Bundle savedInstanceState) {
...
if (savedInstanceState == null){
mSubFragment = new SubFragment();
//add child fragment
getChildFragmentManager()
.beginTransaction()
.add(R.id.fragment_sub, mSubFragment, "tag")
.commit();
}
}
}
or you can add child fragment to Fragmentin onCreatemethod
或者您可以Fragment在onCreate方法中 添加子片段
