在nestedscrollview的recyclerview内部的recyclerview的notifyDataChanged上，外部recyclerview滚动到顶部

Question

I have a recyclerview(2) inside a recyclerview(1) which is inside a nestedscrollview. When I call notifyDataChanged() on 2nd recyclerview the 1st recyclerview scrolls to the top.

Activity with 1st recycler view

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.LinearLayoutCompat xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context="com.practicemock.practicemock.views.QuizActivity">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/quiz_question_rv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            app:layoutManager="android.support.v7.widget.LinearLayoutManager" />

        <android.support.v7.widget.AppCompatButton
            android:id="@+id/sign_up_button"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@drawable/button_background_take_tests"
            android:elevation="3dp"
            android:layout_marginTop="8dp"
            android:layout_marginBottom="16dp"
            android:layout_marginLeft="8dp"
            android:layout_marginRight="8dp"
            android:textAllCaps="false"
            android:text="Submit"
            android:textColor="@android:color/white" />

    </android.support.v7.widget.LinearLayoutCompat>
</android.support.v4.widget.NestedScrollView>

1st recyclerview item with 2nd recyclerview

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="8dp">

    <android.support.v7.widget.LinearLayoutCompat
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <android.support.v7.widget.AppCompatTextView
            fontPath="fonts/heebo/Heebo-Medium.ttf"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginBottom="9dp"
            android:layout_marginLeft="16dp"
            android:layout_marginRight="16dp"
            android:layout_marginTop="16dp"
            android:text="Q.1"
            android:textColor="#5f6d81"
            android:textSize="14sp" />

        <android.support.v7.widget.AppCompatTextView
            fontPath="fonts/heebo/Heebo-Medium.ttf"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="16dp"
            android:layout_marginRight="16dp"
            android:text="The length of train is 120 metres and it crosses a man in 10 second. Find the speed of train."
            android:textColor="@color/textColorDark"
            android:textSize="16sp" />


        <android.support.v7.widget.RecyclerView
            android:id="@+id/quiz_option_rv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginBottom="16dp"
            android:layout_marginTop="16dp"
            android:orientation="vertical"
            app:layoutManager="android.support.v7.widget.LinearLayoutManager" />

    </android.support.v7.widget.LinearLayoutCompat>

</android.support.v7.widget.CardView>

2nd recyclerview item

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.LinearLayoutCompat xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/quiz_option_ll"
    android:background="@drawable/selected_row"
    android:clickable="true"
    android:orientation="horizontal">

    <android.support.v7.widget.AppCompatTextView
        android:id="@+id/option_number_tv"
        android:layout_width="32dp"
        android:layout_height="32dp"
        android:layout_marginRight="20dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="12dp"
        android:layout_marginBottom="12dp"
        android:background="@drawable/circle"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="A"
        android:textColor="@color/textColorMedium"
        android:textSize="14sp" />

    <android.support.v7.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginRight="16dp"
        android:layout_gravity="center"
        android:text="40km/hour"
        android:textColor="@color/textColorDark"
        android:textSize="16sp" />
</android.support.v7.widget.LinearLayoutCompat>

Activity class

public class QuizActivity extends AppCompatActivity {

    @BindView(R.id.quiz_question_rv)
    RecyclerView quizQuestionRV;

    RVQuizQuestionAdapter quizQuestionAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_quiz);
        ButterKnife.bind(this);
        quizQuestionAdapter = new RVQuizQuestionAdapter(this);
        quizQuestionRV.setNestedScrollingEnabled(false);
        quizQuestionRV.setAdapter(quizQuestionAdapter);
    }
}

1st recyclerview adapter

public class RVQuizQuestionAdapter extends RecyclerView.Adapter<RVQuizQuestionAdapter.RVQuizQuestionViewHolder> {

    private QuizActivity context;

    public RVQuizQuestionAdapter(QuizActivity context) {
        this.context = context;
    }

    @Override
    public RVQuizQuestionViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_view_quiz_question, parent, false);
        return new RVQuizQuestionViewHolder(v);
    }

    @Override
    public void onBindViewHolder(RVQuizQuestionViewHolder holder, int position) {

    }

    @Override
    public int getItemCount() {
        return 6;
    }

    public class RVQuizQuestionViewHolder extends RecyclerView.ViewHolder {
        RecyclerView quizOptionRV;
        RVQuizOptionAdapter rvQuizOptionAdapter;
        RVQuizQuestionViewHolder(View itemView) {
            super(itemView);
            quizOptionRV = itemView.findViewById(R.id.quiz_option_rv);
            rvQuizOptionAdapter = new RVQuizOptionAdapter(context);
            quizOptionRV.setNestedScrollingEnabled(false);
            quizOptionRV.setAdapter(rvQuizOptionAdapter);
        }
    }
}

2nd recyclerview adapter

public class RVQuizOptionAdapter extends RecyclerView.Adapter<RVQuizOptionAdapter.RVQuizOptionViewHolder> {

    SparseBooleanArray selectedItems = new SparseBooleanArray();
    private QuizActivity context;

    public RVQuizOptionAdapter(QuizActivity context) {
        this.context = context;
    }

    @Override
    public RVQuizOptionViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_view_quiz_option, parent, false);
        return new RVQuizOptionViewHolder(v);
    }

    @Override
    public void onBindViewHolder(final RVQuizOptionViewHolder holder, int position) {
        if (selectedItems.get(position, false)) {
            holder.optionNumberTV.setText("");
            holder.optionNumberTV.setBackground(ContextCompat.getDrawable(context, R.drawable.circle_tick));
        } else {
            holder.optionNumberTV.setBackground(ContextCompat.getDrawable(context, R.drawable.circle));
            holder.optionNumberTV.setText(getCharForNumber(position));
        }
        holder.quizOptionLL.setSelected(selectedItems.get(position, false));
    }

    @Override
    public int getItemCount() {
        return 4;
    }

    public class RVQuizOptionViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        AppCompatTextView optionNumberTV;
        LinearLayoutCompat quizOptionLL;

        RVQuizOptionViewHolder(View itemView) {
            super(itemView);
            optionNumberTV = itemView.findViewById(R.id.option_number_tv);
            quizOptionLL = itemView.findViewById(R.id.quiz_option_ll);
            quizOptionLL.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            for (int i = 0; i < getItemCount(); i++) {
                selectedItems.put(i, false);
            }
            selectedItems.put(getAdapterPosition(), true);
            notifyDataSetChanged();
        }
    }

    private String getCharForNumber(int i) {
        return i > -1 && i < 26 ? String.valueOf((char) (i + 65)) : null;
    }
}

Please tell me how to stop the scroll of 1st recyclerview. Thanks in advance.

Answer 1

Add this code :

 adapter.notifyItemRangeChanged(0, adapter.getItemCount());

Solution Here

Answer 2

I like to suggest you to put recyclerView.setNestedScrollingEnabled(false); before setting each adapter and for the inner recyclerView set adapter in onBindViewHolder . Hope these will fix your problems.