Error using the RecyclerView: The specified child already has a parent

Question

I am trying to create a listView with a new RecyvlerView Adapter. I have followed the exact guide present on android developer resources. But this is giving me a strange error: The specified child already has a parent. You must call removeView() on the child's parent first. I have the latest SDK. I also define dependencies in gradle.

MyActivity (Main Activity):

public class MyActivity extends Activity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());

        // specify an adapter (see also next example)
        mAdapter = new MyAdapter(new String[]{"Zain", "Nadeem"});

        mRecyclerView.setAdapter(mAdapter);
    }
}

MyAdapter :

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    private String[] mDataset;    
    // Provide a reference to the views for each data item
    // Complex data items may need more than one view per item, and
    // you provide access to all the views for a data item in a view holder
    // Provide a suitable constructor (depends on the kind of dataset)
    public MyAdapter(String[] myDataset) {
        mDataset = myDataset;
    }

    // Create new views (invoked by the layout manager)
    @Override
    public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // create a new view
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());  

        View v = inflater.inflate(R.layout.my_text_view, parent, true);
        ViewHolder vh = new ViewHolder(v);
        return vh;
    }

    // Replace the contents of a view (invoked by the layout manager)
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // - get element from your dataset at this position
        // - replace the contents of the view with that element    
        holder.mTextView.setText(mDataset[position]);
    }

    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {
        return mDataset.length;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        // each data item is just a string in this case
        public TextView mTextView;
        public ViewHolder(View v) {
            super(v);
            mTextView = (TextView) v.findViewById(R.id.item_title);
        }
    }
}

my_text_view.xml (layout for list items):

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="80dp"

    >
    <!-- title -->
    <TextView
        android:id="@+id/item_title"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="@android:color/darker_gray"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="8dp"
        android:textSize="22dp" />

</RelativeLayout>

activity_my.xml (main activity):

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_height="fill_parent"
    android:layout_width="fill_parent"
    android:background="@android:color/holo_orange_light"
    >
    <!-- A CardView that contains a TextView -->
    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MyActivity"/>
    </LinearLayout>

And here is the logcat output:

10-28 01:20:30.287  22729-22729/osman.zaingz.com.lollipop E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: osman.zaingz.com.lollipop, PID: 22729
    java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
            at android.view.ViewGroup.addViewInner(ViewGroup.java:3562)
            at android.view.ViewGroup.addView(ViewGroup.java:3415)
            at android.view.ViewGroup.addView(ViewGroup.java:3360)
            at android.support.v7.widget.RecyclerView$4.addView(RecyclerView.java:322)
            at android.support.v7.widget.ChildHelper.addView(ChildHelper.java:79)
            at android.support.v7.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:4845)
            at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4803)
            at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4791)
            at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1316)
            at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1265)
            at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:522)
            at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:1918)
            at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:2155)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
            at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1660)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1436)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:374)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1983)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1740)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
            at android.view.Choreographer.doCallbacks(Choreographer.java:574)
            at android.view.Choreographer.doFrame(Choreographer.java:544)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)

Answer 1

when inflating you shouldn't attach the view to its parent. you wrote:

View v = inflater.inflate(R.layout.my_text_view, parent, true);

which should be :

View v = inflater.inflate(R.layout.my_text_view, parent, false);

Answer 2

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="80dp">

<TextView
    android:id="@+id/item_title"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textColor="@android:color/darker_gray"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:layout_marginTop="8dp"
    android:textSize="22dp" />

</RelativeLayout>

RelativeLayout this is parent of your TextView with id item_title. Then when RecyclerView is trying to add TextView that has parent it throw exception.

Try this code:

public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
                                                   int viewType) {
        // create a new view
        Log.d(TAG, "onCreateViewHolder");
        RelativeLayout v = (RelativeLayout)LayoutInflater.from(parent.getContext())
                .inflate(R.layout.list_item, parent, false);
        // set the view's size, margins, paddings and layout parameters
        View view = v.findViewById(R.id.text1);
        v.removeView(view);
        ViewHolder vh = new ViewHolder(view);
        return vh;
    }

Answer 3

It happens too if you scroll really fast your recyclerview. My case was inserting/moving/... items with DiffUtils and calling TransitionManager.beginDelayedTransition(view) on the root layout (and so, the recyclerview) somewhere in my code before the end of recyclerview animations