Question

这是从我的数据库中的一个孩子读取长值的简单方法。

同样的方法也为pojo提供了null。

我做错了什么??? 为什么跳过OnDataChanged（）？

（子路径：UserData / DeviceMgmt / Average :)

这是代码：

public class DevicesUtil {
public final static FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
public final static DatabaseReference dbRefUserData = firebaseDatabase.getReference("UserData");
public final static DatabaseReference dbRefUsers = dbRefUserData.child("Users");
public final static DatabaseReference dbRefDisplayNames = dbRefUserData.child("DisplayNames");
public final static DatabaseReference dbRefDeviceMgmt = dbRefUserData.child("DeviceMgmt");
public final static DatabaseReference dbRefAverage = dbRefDeviceMgmt.child("Average");
public final static DatabaseReference dbRefDevices = dbRefDeviceMgmt.child("Devices");
public final static DatabaseReference dbRefNumberOfAll = dbRefDeviceMgmt.child("NumberOfAll");
public final static DatabaseReference dbRefNumberOfSelected = dbRefDeviceMgmt.child("NumberOfSelected");
public final static DatabaseReference dbRefTotalDownloaded = dbRefDeviceMgmt.child("TotalDownloaded");

    private static long theAverage;

    public static long getAverage() {
        dbRefAverage.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                theAverage = dataSnapshot.getValue(Long.class);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Log.e(TAG, databaseError.getMessage() + ", Exception: ", databaseError.toException());
            }
        });
        return theAverage;
    }

public static User getDbUser(final String uid) {
    // getting User value:
    dbRefUsers.child(uid).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange (DataSnapshot dataSnapshot) {
            userValue = dataSnapshot.getValue(User.class);
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
            Log.e(TAG, databaseError.getMessage() + ", Exception: ", databaseError.toException());
        }
    });

}}

和Json：

＆＃34;的UserData＆＃34; ：{ ＆＃34; DeviceMgmt＆＃34; ：{ ＆＃34;平均＆＃34; ：666，＆＃34;器件＆＃34; ：{ ＆＃34; -LEPhxstDLC-SJKITtCI＆＃34; ：{ ＆＃34;下载＆＃34; ：0，＆＃34;故障＆＃34; ：0，＆＃34; fcmToken＆＃34; ：＆＃34; dRneV＆＃34;，＆＃34; signOutTime＆＃34; ：0，＆＃34;予以选取＆＃34; ：真的，＆＃34; UID＆＃34; ：＆＃34; AsU7GKtuTSZFwm3ePwvk4s3AEbT2＆＃34;，＆＃34;使用＆＃34; ：0 }，＆＃34;装置＆＃34; ：＆＃34;虚拟＆＃34; }，＆＃34; NumberOfAll＆＃34; ：8，＆＃34; NumberOfSelected＆＃34; ：8，＆＃34; TotalDownloaded＆＃34; ：0 }，＆＃34; DisplayNames＆＃34; ：{ ＆＃34; Pablo X＆＃34; ：＆＃34; tWlLHuDgGVPr0ZivEEpIi4tik352＆＃34;，＆＃34; Pablo XY＆＃34; ：＆＃34; 0HW3pcWHU9YuPYM4Od4YBqDzB8C3＆＃34;，＆＃34;的Pawel＆＃34; ：＆＃34; AsU7GKtuTSZFwm3ePwvk4s3AEbT2＆＃34;，＆＃34;显示名＆＃34; ：＆＃34;虚拟＆＃34; }，＆＃34;用户＆＃34; ：{ ＆＃34; AsU7GKtuTSZFwm3ePwvk4s3AEbT2＆＃34; ：{ ＆＃34; deviceKey＆＃34; ：＆＃34; -LEPhxstDLC-SJKITtCI＆＃34;，＆＃34;显示名＆＃34; ：＆＃34; Pawel＆＃34;，＆＃34;电子邮件＆＃34; ：＆＃34; email@gmail.com"，＆＃34;轮廓＆＃34; ：＆＃34;用户＆＃34;，＆＃34; signOutTime＆＃34; ：0 }，＆＃34;用户＆＃34; ：＆＃34;虚拟＆＃34; } } }

为什么永远不会调用onDataChange（）

0 个答案: