public class MainFragment extends Fragment {


private RecyclerView mRecyclerView;


@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


}

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

    mRecyclerView = (RecyclerView) view.findViewById(R.id.rv_recycler_view);

    mRecyclerView.setHasFixedSize(true);

    mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

    mRecyclerView.setAdapter(new MyAdapter(new String[]{"test one", "test two", "test three", "test four", "test five", "test six", "test seven"}));

    return view;
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

}

}

public  class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

    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
    static class MyViewHolder extends RecyclerView.ViewHolder {
        CardView mCardView;
        TextView mTextView;

        MyViewHolder(View v) {
            super(v);

            mCardView = (CardView) v.findViewById(R.id.card_view);
            mTextView = (TextView) v.findViewById(R.id.tv_text);
        }
    }

    // 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.MyViewHolder onCreateViewHolder(ViewGroup parent,
                                                     int viewType) {
        // create a new view
        View v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_item, parent, false);
        // set the view's size, margins, paddings and layout parameters
        return new MyViewHolder(v);
    }

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

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

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
   <android.support.v7.widget.RecyclerView
    android:id="@+id/rv_recycler_view"
    android:layout_width="0dp"
    tools:layout_constraintRight_creator="1"
    tools:layout_constraintBottom_creator="1"
    android:layout_marginStart="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    android:layout_marginEnd="8dp"
    app:layout_constraintRight_toRightOf="parent"
    tools:layout_constraintLeft_creator="1"
    app:layout_constraintLeft_toLeftOf="parent"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    tools:listitem="@layout/card_item"
    android:layout_marginTop="8dp"
    app:layout_constraintTop_toTopOf="parent"
    android:layout_marginBottom="8dp"
    android:layout_height="0dp"
    android:scrollbars="vertical"
    android:background="@android:color/white">
</android.support.v7.widget.RecyclerView>