android - 在哪里调用 getChildFragmentManager()？

Question

问题

根据 Google 的文档:

You can now embed fragments inside fragments. This is useful for a variety of situations in which you want to place dynamic and re-usable UI components into a UI component that is itself dynamic and re-usable. For example, if you use ViewPager to create fragments that swipe left and right and consume a majority of the screen space, you can now insert fragments into each fragment page. To nest a fragment, simply call getChildFragmentManager() on the Fragment in which you want to add a fragment. This returns a FragmentManager that you can use like you normally do from the top-level activity to create fragment transactions. For example, here’s some code that adds a fragment from within an existing Fragment class:

Fragment videoFragment = new VideoPlayerFragment();
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.add(R.id.video_fragment, videoFragment).commit();

所以我有(例如)TestFragment，它看起来像:

public class TestFragment extends Fragment {

    private View mFragmentView;
    private FrameLayout mFrameLayout;   

    public HistoryFragment() {
        super();
    }       

    @Override   
    public View onCreateView(LayoutInflater pInflater, ViewGroup pViewGroup, Bundle pBundle) {          

        mFragmentView = pInflater.inflate(R.layout.fragment_layout, pViewGroup, false);         

        mFrameLayout = (FrameLayout) mFragmentView.findViewById(R.id.framelayout);

        return mFragmentView;
    }   

    public void onDestroyView() {
        super.onDestroyView();
    }    

    /* ISSUE */
    public void doSomethingSpecial() {
        FragmentManager tFragmentManager = getChildFragmentManager();
    }
}

在 MainActivity 中，我像这样初始化 fragment :

mTestFragment = new TestFragment();
mTestFragment.doSomethingSpecial();

然后我通过 FragmentPagerAdapter 将 fragment 传递给 ViewPager。

最后，我得到了一个异常(exception)。但如果我只使用:

mTestFragment = new TestFragment();

然后就可以了。

问题

我应该在 fragment 中的什么地方调用 getChildFragmentManager() 方法？我做错了什么？

如果您有使用新的 Android 嵌套 fragment 的好示例，请与我分享链接。非常感谢您的帮助。

Answer 1

简短回答:我在 Fragment 的 onViewCreated() 方法中调用并使用了 getChildFragmentManager()。

例如:

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    addInnerFragment(); // This method does the getChildFragmentManager() stuff.
}