如何從Firebase數據庫檢索數據

Question

我一直在使用Android和Firebase創建移動應用程序，我無法從Firebase獲取數據，問題出在線Survey survey = ds.getValue(Survey.class);，它只在刪除屬性選項和時間戳時才起作用，這裏是我的代碼：

private FirebaseDatabase firebaseDatabase=FirebaseDatabase.getInstance(); 
private DatabaseReference mRootReference=firebaseDatabase.getReference(); 
private DatabaseReference mSurveysReference=mRootReference.child("surveys"); 


    mSurveysReference.addChildEventListener(new ChildEventListener() { 
     @Override 
     public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
      for (DataSnapshot ds:dataSnapshot.getChildren()){ 
       Survey survey = ds.getValue(Survey.class); 
       surveys.add(survey); 
      } 
     } 

     @Override 
     public void onChildChanged(DataSnapshot dataSnapshot, String s) { 

     } 
    }); 

public class Survey { 
    public boolean acceptAnonymousVotes; 
    public boolean enabled; 
    public String id; 
    public String image; 
    public Option[] options ; 
    public boolean resultPublic; 
    public Timestamp timeStamp; 
    public String title; 
    public int totalComments; 
    public int totalViews; 
    public int totalVotes; 
    public String type; 
    public String userId; 
public Survey() { 
} 
} 

public class Option { 
    public int id ; 
    public String title ; 
} 

Answer 1

據https://firebase.google.com/docs/database/android/read-and-write，你需要需要調用DataSnapshot.getValue一個默認的構造函數（XY.class）

還可以使用List<Option>而不是Options[]來選擇。