如何在RecyclerView中显示Firebase数据库的变量“名称”和“值”

Question

提取数据：

    private void fetchResults() {
    mDatabaseReference.child("Users").child(id).child("Quiz").child("Results").child(id).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot resultSnapshot: dataSnapshot.getChildren()) {
                String user = resultSnapshot.getKey();
                String score = resultSnapshot.getValue(String.class);
                Results results = new Results(user, score);
                resultsList.add(results);
            }
            mAdapter.notifyDataSetChanged();

                    }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            throw databaseError.toException();
        }
    });
}

保存数据：

 String name = RecieversName;
                HashMap<String, String> userMap = new HashMap<>();
                userMap.put(name, String.valueOf(mScore));
                mRef.child("Users").child(RecieversId).child("Quiz").child("Results").child(UID).setValue(userMap).addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        if (task.isSuccessful()) {
                            Intent intent = new Intent(TakingQuiz.this, TakingQuizDone.class);
                            intent.putExtra("RecieversId",RecieversId);
                            intent.putExtra("Score", mScore.toString());
                            startActivity(intent);
                            finish();
                        }
                    }
                });

适配器：

public class AdapterQuiz extends RecyclerView.Adapter<AdapterQuiz.ResultViewHolder>{

private FirebaseAuth mAuth;
private List<Results> mResultsList;

public AdapterQuiz(List<Results>mResultsList)

    {
    this.mResultsList = mResultsList;
    }

public class ResultViewHolder extends RecyclerView.ViewHolder{
public TextView name;
public TextView score;
public ResultViewHolder(View view)
{
    super(view);
    name = (TextView)view.findViewById(R.id.name);
    score = (TextView)view.findViewById(R.id.score);
}
}
@Override
public ResultViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
    View V = LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_activity_results,parent,false);
    mAuth = FirebaseAuth.getInstance();
    return new ResultViewHolder(V);
}


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

    Results results = mResultsList.get(position);

    holder.name.setText(results.getName());
    holder.score.setText(results.getScore());
}


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

}

结果类

public class Results {
private String Name;
private String Score;

public Results() {
}

public Results(String Name, String Score) {
    this.Name = Name;
    this.Score = Score;
}

public String getName() {
    return Name;
}

public void setName(String name) {
    Name = name;
}

public String getScore() {
    return Score;
}

public void setScore(String score) {
    Score = score;
}

}

我已经有一段时间在RecyclerView和Firebase上工作了，但是通常我会显示一个常量“名称”和一个变量“值”，但是这里的名称和变量都不由我决定...当用户完成测验时，他的分数将是显示在recyclerview中，但显示为空白而没有任何错误...我不确定这是否是获取此类数据的正确方法...任何人都可以帮帮我吗

数据库-https: //ibb.co/eMWkFJ

Answer 1

Results results;
String name, score;
private void fetchResults() {
    mDatabaseReference.child("Users").child(id).child("Quiz").child("Results").child(id).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
             for (DataSnapshot childDataSnapshot : dataSnapshot.getChildren()) {
                 name = childDataSnapshot.getKey().toString();
                 score = childDataSnapshot.child(name).getValue());
                 results = new Results(user, score);
                 resultsList.add(results);
                 mAdapter.notifyDataSetChanged();
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
            throw databaseError.toException();
        }
    });
}

我希望这能做好您的工作。

Answer 2

要解决此问题，您首先需要设置适配器，然后再通知其更改。 因此，请使用以下代码行：

mRecyclerView.setAdapter(mAdapter);

代替这个：

mAdapter.notifyDataSetChanged();

仅当数据库中发生某些更改时才应使用最后一行代码，并且为了通知适配器，必须在第一位置进行设置。