Question

因为我能够从Firebase检索数据，但是对于Android中的单用户数据库。我只想从没有用户身份验证登录的情况下从firebase插入的数据库中获取数据。

我在logcat中遇到错误：

(Me.Ocjena1 = 2 Or Me.Ocjena1 = 3 Or Me.Ocjena1 = 4 Or Me.Ocjena1 = 5)

这是我的代码：

With Me
If .Ocjena1 > 1 And .Ocjena1 < 6 Then
    If .Ocjena2 = 1 And IsNull(.Ocjena3) Then
        .Konacna_ocjena = 1
    ElseIf .Ocjena2 > 1 And .Ocjena2 < 6 And IsNull(.Ocjena3) Then
        .Konacna_ocjena = (.Ocjena1 + .Ocjena2) / 2
    ElseIf .Ocjena2 = 1 And .Ocjena3 > 1 And .Ocjena3 < 6 Then
        .Konacna_ocjena = (.Ocjena1 + .Ocjena3) / 3
    ElseIf IsNull(.Ocjena2) And IsNull(.Ocjena3) Then
        .Konacna_ocjena = .Ocjena1
End If
End With

这是我的用户信息代码：

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference

Answer 1

使用迭代器，您将能够完成此任务。

 public void onDataChange(DataSnapshot dataSnapshot) {
                  for(DataSnapshot data: dataSnapshot.getChildren()){
                userinfo  user = data.getValue(userinfo.class);
                Log.d(TAG, "User name: " + user.getName() + ", mobile: " 
     + user.getMob() + ", Vehicle " + user.getVehicle() + ", Address " + 
     user.getAdd());}
            }

能够从Android中的Firebase数据库中检索数据，但仅限单个用户

1 个答案: