Instead of parsing the json response manually.
Paste you json here http://www.jsonschema2pojo.org/ and use GSON or Jackson whichever is convenient for parsing the response.
There are many tutorials available which can give you a quick overview of how things can be done. Worth a try if your app has many places where you want to have Json parsing.

I have two forloop in which the data is added to different ArrayList. Now my question is how do we combine these two arraylist?
Below is the code which i tried, but not working. Please give me solution for the same. TIA

try {
        JSONObject object = new JSONObject(response);
        status = object.getString("status");
        if (status.equals("200")) {
            rest.dismissProgressdialog();
            JSONArray jsonArray = object.getJSONArray("data");

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                New_Service_Model_1 new_service_model = new New_Service_Model_1();
                new_service_model.setMain_name(jsonObject.getString("main_name"));
                new_service_model.setSmid(jsonObject.optInt("smid"));

                JSONArray jsonArray1 = jsonObject.getJSONArray("sub_service");

                //sub_services_list.clear();
                sub_services_list = new ArrayList<>();
                for (int j = 0; j < jsonArray1.length(); j++) {
                    JSONObject jsonObject1 = jsonArray1.getJSONObject(j);
                    New_Sub_Service_Model_1 sub_service_model = new New_Sub_Service_Model_1();
                    sub_service_model.setSmid(jsonObject1.optString("smid"));
                    sub_service_model.setSbid(jsonObject1.optInt("sbid"));
                    sub_service_model.setSub_name(jsonObject1.optString("sub_name"));
                    sub_service_model.setDesc(jsonObject1.optInt("desc"));
                    sub_service_model.setSt_cust(jsonObject1.optInt("st_cust"));
                    sub_service_model.setSt_pro(jsonObject1.optInt("st_pro"));
                    sub_service_model.setExist_cust(jsonObject1.optInt("exist_cust"));
                    sub_service_model.setExist_prov(jsonObject1.optInt("exist_prov"));
                    sub_services_list.add(sub_service_model);

                }
                new_service_model.setSub_service_list(sub_services_list);
                services_list.add(new_service_model);
                service_list_adapter = new Service_List_Adapter_1(this, services_list, service_costMain_interface);
                rclyrview_services.setAdapter(service_list_adapter);
                service_list_adapter.notifyDataSetChanged();
            }
        } else {
            rest.dismissProgressdialog();
            Toast.makeText(Service_Manage.this, "No Data found", Toast.LENGTH_SHORT).show();
        }