Android : Create JSON android

I want to have an output like this

{"content":{
     "A":["a1","a2","a3"],
     "B":"b1String",
     "C":["c1","c2"]}}

As of now, I am getting this.

{"content":{
     "A":"[a1, a2, a3]",
     "C":"[c1, c2]",
     "B":"b1String"}}

Below is my code

Map <String, Object> myMap =  new HashMap<String, Object>();

myMap.put("A",arrayOfA); //which is ArrayList<String>
myMap.put("B", myB1String);//which is String
myMap.put("C", arrayOfC);//which is ArrayList<String>

JSONObject jsonAll = new JSONObject(myMap);

Map <String, Object> mapAll =  new HashMap<String, Object>();
mapAll.put("content", jsonAll);

JSONObject finalObject=new JSONObject(mapAll);
Log.e("JSON", finalObject.toString());

Any help woulld be much appreciated. Thanks