How can i get Strings from a complex JSON Object without a JSON Array

i have understood how to get a JSON Array. but i dont know how to get here is the link to the JSON file. https://www.cryptocompare.com/api/data/coinlist
or

{"Response":"Success","Message":"Coin list succesfully returned!","BaseImageUrl":"https://www.cryptocompare.com","BaseLinkUrl":"https://www.cryptocompare.com","DefaultWatchlist":{"CoinIs":"1182,7605,5038,24854,3807,3808,202330,5324,5031,178978","Sponsored":"1182"},"Data":{"USC":{"Id":"100954","Url":"/coins/usc/overview","ImageUrl":"/media/1383363/usc.png","Name":"USC","Symbol":"USC","CoinName":"Ultimate Secure Cash","FullName":"Ultimate Secure Cash (USC)","Algorithm":"SHA256","ProofType":"PoS","FullyPremined":"0","TotalCoinSupply":"200084200","PreMinedValue":"N/A","TotalCoinsFreeFloat":"N/A","SortOrder":"1233","Sponsored":false},"DUX":{"Id":"105206","Url":"/coins/dux/overview","ImageUrl":"/media/1383364/dux.png","Name":"DUX","Symbol":"DUX","CoinName":"DuxCoin","FullName":"DuxCoin (DUX)","Algorithm":"Scrypt","ProofType":"PoW/PoS","FullyPremined":"0","TotalCoinSupply":"1680000000","PreMinedValue":"N/A","TotalCoinsFreeFloat":"N/A","SortOrder":"1234","Sponsored":false},"XPS":{"Id":"105220","Url":"/coins/xps/overview","ImageUrl":"/media/1383365/xps.png","Name":"XPS","Symbol":"XPS","CoinName":"PoisonIvyCoin","FullName":"PoisonIvyCoin (XPS)","Algorithm":"Scrypt","ProofType":"PoW/PoS","FullyPremined":"0","TotalCoinSupply":"4666666667","PreMinedValue":"N/A","TotalCoinsFreeFloat":"N/A","SortOrder":"1235","Sponsored":false},"EQT":{"Id":"105263","Url":"/coins/eqt/overview","ImageUrl":"/media/1383366/eqt.png","Name":"EQT","Symbol":"EQT","CoinName":"EquiTrader","FullName":"EquiTrader (EQT)","Algorithm":"Scrypt","ProofType":"PoW","FullyPremined":"0","TotalCoinSupply":"72000000","PreMinedValue":"N/A","TotalCoinsFreeFloat":"N/A","SortOrder":"1236","Sponsored":false},"INSN":{"Id":"105284","Url":"/coins/insn/overview","ImageUrl":"/media/1383366/insn.png","Name":"INSN","Symbol":"INSN","CoinName":"Insane Coin","FullName":"Insane Coin (INSN)","Algorithm":"X11","ProofType":"PoW/PoS","FullyPremined":"0","TotalCoinSupply":"30000000","PreMinedValue":"N/A","TotalCoinsFreeFloat":"N/A","SortOrder":"1237","Sponsored":false}},"Type":100}

Symbol,
FullName and
CoinName this is my code

  try {
            // Hashmap for ListView
            ArrayList<HashMap<String, String>> PriceList = new ArrayList<HashMap<String, String>>();

            JSONObject jsonObj = new JSONObject(json);





            JSONObject mJ = jsonObj.getJSONObject("Response");




            for (int i = 0; i < json.length(); i++) {
                JSONObject c = mJ.getJSONObject("Data");

                String  symbol = c.getString("Symbol");
                String  fName =  c.getString("FullName");
                String  cName =  c.getString("CoinName");


                // tmp hashmap for single data
                HashMap<String, String> data = new HashMap<>();

                // adding each child node to HashMap key => value
                data.put("Symbol",symbol);
                data.put("FullName",fName);
                data.put("CoinName",cName);

                // adding data to listView
                PriceList.add(data);
            }
            return PriceList;
        } catch (JSONException e) {
            e.printStackTrace();
            return null;
        }
    } else {
        Log.e("ServiceHandler", "Couldn't get any data from the url");
        return null;
    }