Question

这是我的数据树：

"look-twopointo": {
    "0" {
        "comment": "Hi"
        "Text1": "Hello"
        "Text2": "Bonsoir"
        "type": "Bonjour"
        "version": "4.0.6"
    }
}

由于某些原因，查询无效。

button.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        mDatabase = FirebaseDatabase.getInstance().getReference().child("0");// pay attention to the this path reference
        // Read from the database
        Query query = mDatabase.child("version")/*.orderByChild("Text1")*/.equalTo("4.0.6")/*.startAt("d")/*.endAt("Dude")*/;
        query.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                // This method is called once with the initial value and again
                // whenever data at this location is updated.
                //String value = dataSnapshot.getValue(String.class); //these three lines below are probably the problem
                String value = (String) dataSnapshot.getValue();
                System.out.println(value);
                Text.setText(value);
            }

以下是系统吐出的内容：

D/ViewRootImpl: ViewPostImeInputStage processPointer 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 1
I/DynamiteModule: Considering local module 
com.google.android.gms.firebase_database:4 and remote module 
com.google.android.gms.firebase_database:6
              Selected remote version of 
com.google.android.gms.firebase_database, version >= 6
D/ResourcesManager: For user 0 new overlays fetched Null
W/System: ClassLoader referenced unknown path: 
/data/data/com.google.android.gms/app_chimera/m/0000005e/n/armeabi-v7a
      ClassLoader referenced unknown path: 
/data/data/com.google.android.gms/app_chimera/m/0000005e/n/armeabi
D/ResourcesManager: For user 0 new overlays fetched Null
I/System.out: null

我不知道是不是因为我正在使用手机并且没有下载并在模拟器上试过它。有什么我必须设置，以便我可以在我的手机上查询？

这是可能导致此

的错误

05-28 17:12:42.743 2449-3078/? E/NetlinkEvent: NetlinkEvent::FindParam(): Parameter 'LABEL' not found
NetlinkEvent::FindParam(): Parameter 'UID' not found

或者我是这个

W/System: ClassLoader referenced unknown path: 
/data/data/com.google.android.gms/app_chimera/m/0000005e/n/armeabi-v7a
          ClassLoader referenced unknown path: 
/data/data/com.google.android.gms/app_chimera/m/0000005e/n/armeabi

我希望它输出4.0.6。

更新：我实际上找不到错误。它为NO REASON输出null

Answer 1

要解决此问题，您需要将查询更改为：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Query query = rootRef.orderByChild("version").equalTo("4.0.6");

并将返回version属性与4.0.6相等的所有记录。

Firebase查询方法不起作用

1 个答案: