ViewHolder views must not be attached when created

Question

I'm trying to create a simple RV that will show a TextView. This is my adapter:

public class MyRvAdapter extends RecyclerView.Adapter<MyRvAdapter.ViewHolder> {

private String[] mDataset;


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

public MyRvAdapter(String[] myDataset) {
    mDataset = myDataset;
}

@NonNull
@Override
public MyRvAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.text_row_item, parent, false);
    TextView userNameInList= v.findViewById(R.id.display_name);
    ViewHolder vh = new ViewHolder(userNameInList);
    return vh;
    }

@Override
public void onBindViewHolder(@NonNull MyRvAdapter.ViewHolder holder, int position) {
    holder.mTextView.setText(mDataset[position]);
}

@Override
public int getItemCount() {
    return mDataset.length;
}

}

text_row_item is just a FrameLayout with a TextView inside it("display_name"). This is the eror:

java.lang.IllegalStateException: ViewHolder views must not be attached when created. Ensure that you are not passing 'true' to the attachToRoot parameter of LayoutInflater.inflate(..., boolean attachToRoot)
    at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6687)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5869)

Thank you very much!

Answer 1

Actually, your ViewHolder expects a View inflated from R.layout.text_row_item rather than a descendant of the latter. So, if you pass the inflated view the problem will be resolved.

So, you should correct your code to this:

public class MyRvAdapter extends RecyclerView.Adapter<MyRvAdapter.ViewHolder> {

    private String[] mDataset;

    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 = v.findViewById(r.id.display_name);
        }
    }

    public MyRvAdapter(String[] myDataset) {
        mDataset = myDataset;
    }

    @NonNull
    @Override
    public MyRvAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.text_row_item, parent, false);
        ViewHolder vh = new ViewHolder(v);
        return vh;
    }

    @Override
    public void onBindViewHolder(@NonNull MyRvAdapter.ViewHolder holder, int position) {
        holder.mTextView.setText(mDataset[position]);
    }

    @Override
    public int getItemCount() {
        return mDataset.length;
    }
}

Answer 2

Wait till view is created before binding.

Remove TextView userNameInList= v.findViewById(R.id.display_name); from your MyRvAdapter.ViewHolder.

And bind in ViewHolder as mTextView = v.findViewById(r.id.display_name);.