This is an example for how to handle dynamic key for response. Here A and B are dynamic keys it can be anything

Response

{
  "response": [
    {
      "A": [
        {
          "name": "Tango"
        },
        {
          "name": "Ping"
        }
      ],
      "B": [
        {
          "name": "Jon"
        },
        {
          "name": "Mark"
        }
      ]
    }
  ]
}

Java code

// ResponseData is raw string of response
JSONObject responseDataObj = new JSONObject(responseData);
JSONArray responseArray = responseDataObj.getJSONArray("response");
for (int i = 0; i < responseArray.length(); i++) {
    // Nodes ArrayList<ArrayList<String>> declared globally
    nodes = new ArrayList<ArrayList<String>>();
    JSONObject obj = responseArray.getJSONObject(i);
    Iterator keys = obj.keys();
    while(keys.hasNext()) {
       // Loop to get the dynamic key
       String currentDynamicKey = (String)keys.next();
       // Get the value of the dynamic key
       JSONArray currentDynamicValue = obj.getJSONArray(currentDynamicKey);
       int jsonArraySize = currentDynamicValue.length();
       if(jsonArraySize > 0) {
           for (int ii = 0; ii < jsonArraySize; ii++) {
                // NameList ArrayList<String> declared globally
                nameList = new ArrayList<String>();
               if(ii == 0) {
                JSONObject nameObj = currentDynamicValue.getJSONObject(ii);
                String name = nameObj.getString("name");
                System.out.print("Name = " + name);
                // Store name in an array list
                nameList.add(name);
              }
           }                    
       }
     nodes.add(nameList);
    }
}