Tabs in a class that extends fragment

问题:

I'm reading many tutorial how to implement tabs in a class that extends FragmentActivity,
but no one about how to implement tabs in a class that extends Fragment

I created with AndroidStudio a new project with a NavigationDrawerFragment:
this navigationDrawerFragment for every option menu that it displays create a new Fragment. Inside this fragment i need to have some tabs.

how can i add tabs inside onCreateView method of the fragment?
someone can give to me a very simple example?


What i'm doing to try to solve my problem:

Step 1 - i created a new LinearLayout, it contains the tabHost and it's the main fragment:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment1"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TabHost
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tabHost"
        android:layout_gravity="center_horizontal">

        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical">

            <TabWidget
                android:id="@android:id/tabs"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">
            </TabWidget>
            <FrameLayout
                android:id="@android:id/tabcontent"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent">

                <LinearLayout
                    android:id="@+id/tab1"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"
                    android:orientation="horizontal">
                </LinearLayout>
                <LinearLayout
                    android:id="@+id/tab2"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"
                    android:orientation="horizontal">
                </LinearLayout>
                <LinearLayout
                    android:id="@+id/tab3"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"
                    android:orientation="horizontal">
                </LinearLayout>
            </FrameLayout>
        </LinearLayout>
    </TabHost>
</LinearLayout>

Step 2 - on the main fragment I put this rows of code:

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            //View rootView = inflater.inflate(R.layout.vediamo, container, false);

            mTabHost = new FragmentTabHost(getActivity());
            mTabHost.setup(getActivity(), getChildFragmentManager(), R.id.fragment1);

            mTabHost.addTab(mTabHost.newTabSpec("simple").setIndicator("Simple"),
                    CreaAnnoFragment.class, null);
            mTabHost.addTab(mTabHost.newTabSpec("contacts").setIndicator("Contacts"),
                    ModificaAnnoFragment.class, null);
            mTabHost.addTab(mTabHost.newTabSpec("throttle").setIndicator("Throttle"),
                    EliminaAnnoFragment.class, null);

            return mTabHost;
        }

        @Override
        public void onDestroyView() {
            super.onDestroyView();
            mTabHost = null;
        }

If i run the program i get this error:

java.lang.NullPointerException
        at myapps.studentsmarks.CreaAnnoFragment.onAttach(CreaAnnoFragment.java:100)

FIXED - solution
"the wrapped fragment" don't need the onAttach() method and this is logic. So just delete it

回答1:

For that you can use FragmentTabHost class, that let's you add tabs to your Fragment, just as you do for Activities.

Here's an example:

public class FragmentTabsFragmentSupport extends Fragment {
private FragmentTabHost mTabHost;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    mTabHost = new FragmentTabHost(getActivity());
    mTabHost.setup(getActivity(), getChildFragmentManager(), R.id.fragment1);

    mTabHost.addTab(mTabHost.newTabSpec("simple").setIndicator("Simple"),
            FirstFragment.class, null);
    mTabHost.addTab(mTabHost.newTabSpec("contacts").setIndicator("Contacts"),
            SecondFragment.class, null);
    mTabHost.addTab(mTabHost.newTabSpec("throttle").setIndicator("Throttle"),
            ThirdFragment.class, null);

    return mTabHost;
}

@Override
public void onDestroyView() {
    super.onDestroyView();
    mTabHost = null;
}

}

For more information, check the official documentation.