Firebase 无法使用类检索数据

Question

我有一些功能齐全的代码行来检索每个数据，但无法使用类检索它们。例如：这些线路运行良好。

double value = (double) ds.child("player1score").getValue();

long value = (long) ds.child("point").getValue();

但是，在使用类检索时，会发生错误。这是我的代码的全貌，不确定它是否足以解决问题，请随时让我知道还需要什么，非常感谢您的建议，谢谢！

Round().class

public class Round {

public double player1score;

public double player2score;

public double player3score;

public double player4score;

public long point;

//Constructor

public Round(double player1score, double player2score, double player3score, double player4score, long point) {

    this.player1score = player1score;

    this.player2score = player2score;

    this.player3score = player3score;

    this.player4score = player4score;

    this.point = point;

//Below are All the getter and setter etc

}

我的 MainActivity.class.onCreate()

//Declare Variables

UserId = FirebaseAuth.getInstance().getCurrentUser().getUid();

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();

DatabaseReference gameInfoRef = rootRef.child("user").child(UserId).child("gameInfo");

DatabaseReference gameRecordRef = rootRef.child("user").child(UserId).child("gameRecord");

String gameKey = "-LLyXhetqj9mj5fgh9bn";

在 onCreate() 下：

gameRecordRef.child(gameKey).addValueEventListener(new ValueEventListener() {

        @Override

        public void onDataChange(DataSnapshot dataSnapshot) {

            for (DataSnapshot ds : dataSnapshot.getChildren()) {

                ListView lv_history = (ListView) findViewById(R.id.lv_history);

                ArrayList<Round> ResultList = new ArrayList<>();

                //This line is where the error pointed to

                Round round = (Round) ds.getValue(Round.class);

                ResultList.add(round);

                ivd_HistoryAdapter adapter = new ivd_HistoryAdapter(id_History.this, ResultList);

                lv_history.setAdapter(adapter);

            }

        }