在android firebase中获取父节点

您应该getKey()在检索到的方法中调用该方法dataSnapshot:

  final Query userQuery = mRef.orderByChild("First Name");

  userQuery.addChildEventListener(new ChildEventListener() {
     @Override
     public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        map.clear();
        //Get the node from the datasnapshot
        String myParentNode = dataSnapshot.getKey();
        for (DataSnapshot child: dataSnapshot.getChildren())
        {
           String key = child.getKey().toString();
           String value = child.getValue().toString();
           map.put(key,value);
        }