Question

I am trying to make my app more tablet-friendly, and so I’m trying to learn fragments. I want the typical two-pane layout, where the left side is the “navigation”, and you click on one of the elements, and it changes the fragment on the right.

I can duplicate the tutorials that use a ListFragment for the left, and if you click on one of them, it updates the “details” fragment on the right.

I’ve tried the best I can to duplicate that code, and just use a LinearLayout, with buttons for the left side, so that if a button is clicked, it loads the appropriate fragment on the right, but it’s not working.
When I commit the FragmentTransaction, I get java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first. What is the child’s parent, and why do I have to call removeView on it?

I’m trying to load the fragment into a FrameLayout, but I’ve also just tried replacing another Fragment in the layout, and still get the error.

Ideally I want the left fragment to take up the whole screen until a button is pressed that requires a fragment to come in from the left, but one problem at a time I suppose.

Code

Main Activity

public class FragmentExample2Activity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}

SelectorFragment (Left side)

public class SelectorFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View fragment = inflater.inflate(R.layout.selector, container);

        Button button1 = (Button) fragment.findViewById(R.id.button1);

        button1.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {

                getFragmentManager().beginTransaction().replace(R.id.detail_holder, new DetailsFragment(), "stuff").commit();

            }

        });


        return fragment;
    }
}

DetailsFragment

public class DetailsFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        return inflater.inflate(R.layout.details, container);
    }
}

main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <fragment class="com.coreno.testfragment.SelectorFragment"
        android:id="@+id/select"
        android:layout_width="match_parent"
        android:layout_height="match_parent" 
        android:layout_weight="1"
        />

    <fragment class="com.coreno.testfragment.DetailsFragment"
        android:id="@+id/detail_holder"
        android:layout_width="match_parent"
        android:layout_height="match_parent" 
        android:layout_weight="2"
        />
    <!-- 
    <FrameLayout
        android:id="@+id/detail_holder" 
        android:layout_width="0px"
        android:layout_height="match_parent"
        android:layout_weight="2"
        />
 -->
</LinearLayout>

Answer 1

When you inflate a layout xml file, don’t specify the parent view. It sounds very counter-intuitive to not specify where you’re putting this inflated view but it works.

So, for example, in your SelectorFragment change the line:

View fragment = inflater.inflate(R.layout.selector, container);

to

View fragment = inflater.inflate(R.layout.selector, null);

or even better

View fragment = inflater.inflate(R.layout.selector, container, false);

Don’t forget to do the same in your DetailsFragment too.