如何获得用户在列表视图上单击的商品的唯一ID

Question

 DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
    DatabaseReference usersRef = rootRef.child("Users");
    ValueEventListener eventListener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            ListView listView = (ListView) rootView.findViewById(R.id.usersList);
            ArrayAdapter<String> adapter;
            adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, android.R.id.text1, al);
            for(DataSnapshot ds : dataSnapshot.getChildren()) {

                name = ds.child("Name").getValue().toString();
                phonenumber=ds.getKey();
                list_user_id = getRef(position).getKey;
//                    Log.d("TAG", name);
                al.add(name);

            }
            listView.setAdapter(adapter);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            Toast.makeText(getActivity(),"Please Check Your Internet Connection",Toast.LENGTH_SHORT).show();
        }
    };
    usersRef.addListenerForSingleValueEvent(eventListener);

I have a all users activity... If i click on a user i want to fetch their unique id but im unable to do that... error in line - list_user_id = getRef(position).getKey; is my way of fetching id wrong or is the method obsolete?

Answer 1

Since you have a listview you can do the following:

 lists.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            final String selectedFromList = (String)lists.getItemAtPosition(i);
            db= FirebaseDatabase.getInstance().getReference().child("Users");
            db.orderByChild("username").equalTo(selectedFromList).addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for(DataSnapshot data: dataSnapshot.getChildren()){
                            String ids=datas.getKey();
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });



        }
    });

Assuming you have a listview containing usernames and assuming you have this in your db:

 Users
   userid
      username://name
   userid
      username: //name

Using this final String selectedFromList = (String)lists.getItemAtPosition(i); you are able to get the item in this case the username . Then using the query equalTo() it will check the database and return to you the id of that user using getKey()

Answer 2

You can get all the key values from Firebase DB by using Map in onDataChange method like this:

        Map<String, Object> td = null;
        for (com.google.firebase.database.DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
            td = (HashMap<String, Object>) postSnapshot.getValue();
            String userName= (String) td.get("userName");
            String mobileNUM= (String) td.get("mobileNUM");
            }