来自Firebase的数据未显示在RecyclerView上

我正在尝试从Firebase数据库中显示数据，但得到以下信息：我的recyclerview

Firebase数据库。

我一直在寻找不同的解决方案，但我仍然继续回到同样的问题。我对Android和编程领域还是比较陌生，因此对您的帮助将不胜感激。这是相关的代码。

LogbookFragment：

public class LogbookFragment extends Fragment {

private TextView textView;
private CardView cardView;
private String assessment;
private String details;

private RecyclerView rv;
RequestQueue requestQueue;

private List<Assessment> skillsList = new ArrayList<>();

private static final String ARG_SECTION_NUMBER = "position";

/**
 * Returns a new instance of this fragment for the given section
 * number.
 */
public static LogbookFragment newInstance(int position) {
    LogbookFragment fragment = new LogbookFragment();
    Bundle args = new Bundle();
    args.putInt(ARG_SECTION_NUMBER, position);
    fragment.setArguments(args);
    return fragment;
}

public LogbookFragment() {
}

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

    Context context = getActivity();
    cardView = (CardView) rootView.findViewById(R.id.cv);
    rv = (RecyclerView) rootView.findViewById(R.id.rv);

    final LinearLayoutManager llm = new LinearLayoutManager(context);
    rv.setLayoutManager(llm);

    final RVAdapter adapter = new RVAdapter(skillsList);
    rv.setAdapter(adapter);

    initializeData();

    return rootView;
}

private void initializeData(){
    skillsList = new ArrayList<>();
    Firebase ref = new Firebase("https://athenajs.firebaseio.com/assessments");

    final RVAdapter adapter = new RVAdapter(skillsList);


    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            System.out.println(dataSnapshot.getValue());

            for(DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                for (int i = 0; i<42; i++) {
                    assessment = postSnapshot.child("assessment").getChildren().toString();
                    details = postSnapshot.child("details").getChildren().toString();

                    skillsList.add(new Assessment(assessment, details));
                    rv.setAdapter(adapter);
                    adapter.notifyDataSetChanged();
                }

            }

        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {
            System.out.println("The read failed: " + firebaseError.getMessage());
        }
    });
}

}

RVAdapter：

public class RVAdapter extends RecyclerView.Adapter<RVAdapter.AssessViewHolder> {



public static class AssessViewHolder extends RecyclerView.ViewHolder {

    CardView cv;
    TextView assessName;
    TextView pracName;

    AssessViewHolder(View itemView) {
        super(itemView);
        cv = (CardView)itemView.findViewById(R.id.cv);
        assessName = (TextView)itemView.findViewById(R.id.assessment);
        pracName = (TextView) itemView.findViewById(R.id.details);

    }
}

List<Assessment> skill;

RVAdapter(List<Assessment> skills){
    this.skill = skills;
}

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);
}

@Override
public AssessViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.itemlogbook, viewGroup, false);
    AssessViewHolder avh = new AssessViewHolder(v);
    return avh;
}

@Override
public void onBindViewHolder(AssessViewHolder assessViewHolder, int i) {
    assessViewHolder.assessName.setText(skill.get(i).assessment);
    assessViewHolder.pracName.setText(skill.get(i).details);
}

@Override
public int getItemCount() {
    return skill.size();

}

}

评估课：

public class Assessment {
String assessment;
String details;

Assessment(String assessment, String details) {
    this.assessment = assessment;
    this.details = details;

}

public String getAssessment() {
    return assessment;
}

public String getDetails() {
    return details;
}