MakeRequest.java

    public void makeRequest(final String url, final String json) {
        Runnable runable = new Runnable() {
            public void run() {
                try{
                    OkHttpClient client = new OkHttpClient();

                    RequestBody body = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), json);
                    Request request = new Request.Builder()
                            .header("User-Agent", "Mozilla/5.0 (Linux; Android 6.0.1; SM-webview_android_dl Build/MMB29K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.91 Mobile Safari/537.36")
                            .addHeader("Content-Type","application/json")
                            .url(url)
                            .post(body)
                            .build();

                    client.newCall(request).execute();
                }catch(Exception e){
                    e.printStackTrace();
                }
            }
        };
        Thread thread = new Thread(runable);
        thread.start();
    }