Parsing json (android)

Question

I cant parse json string. This is only json object, i cant barse its. I use iterator like this:

JSONObject jsonObject = new JSONObject("test1");
                Iterator<String> iterator = jsonObject.keys();

                while(iterator.hasNext()) {
                    String currentKey = iterator.next();
                    JSONObject obj = jsonObject.optJSONObject(currentKey);
                    if (obj != null) {
                        Iterator<String> iterator2 = obj.keys();
                        Log.e("Iterator 2", iterator2.toString());
                    }
                }

But i have error: `org.json.JSONException: Value sensorTypes of type java.lang.String cannot be converted to JSONObject. My json string:

{ "test1": {
            "1": {
                "action": "0",
                "type": "1",
                "id": "1",
            },
            "2": {
                "action": "0",
                "type": "1",
                "id": "2",
            }
        },
        "test2": {
            "1": {
                "id": "1",
                "name": "one"
            },
            "2": {
                "id": "2",
                "name": "two"
            },
            "5": {
                "id": "5",
                "name": "three"
            }
        }}

How i can parse json like this?