Firebase Android count children/ badge
<p>I try to develop a simple shopping application. There will be a few product categories and I use different activity with ListView for every category. When User choose product category (say items1 ="drinks")- new screen opens and he can add "soda", "cola"... I want to add count badge on every category to show number of products per category.
So, for example for "items" I need to display 5, for "items1" - 2 and for  "items10/11" - display 1:</p>

<p><a href="https://i.stack.imgur.com/pkl5o.png" rel="noreferrer"><img src="https://i.stack.imgur.com/pkl5o.png" alt="enter image description here"></a></p>

<p>my ActivityItems1 code:</p>

<pre><code>       private Firebase mRef;
       private String mUserId;
       private String itemsUrl;
       private TextView badge;


       itemsUrl = Constants.FIREBASE_URL + "/users/" + mUserId + "/items1";



    // Set up LisView
    final ListView listView = (ListView) findViewById(R.id.listView);
    final ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;&gt;(this,     android.R.layout.simple_list_item_1, android.R.id.text1);
    listView.setAdapter(adapter);  

    // Find badge
         badge =(TextView)findViewById(R.id.badgeView);


    // Use Firebase to populate the list.
    new Firebase(itemsUrl)
            .addChildEventListener(new ChildEventListener() {
                @Override
                public void onChildAdded(DataSnapshot dataSnapshot, String   s) {
                    adapter.add((String)     dataSnapshot.child("title").getValue());


     Log.e(dataSnapshot.getKey(),    dataSnapshot.getChildrenCount() + "");

     badge.setText(dataSnapshot.getChildrenCount() + "");
                }
</code></pre>

<p>After running the code I received Key and number of his children:
E-KJGG2driQ6HJI8R7eve: 1
E-KJGG3Ua6rmlQYn4IHF: 1</p>

<p>it's always 1 child for every Key because Key=Product ID and child of the Key - it's title. <strong>But I need to count Keys/ Product IDs (products in category "drinks") and not his children</strong>...</p>