class APIResponseObject{
    int responseCode;
    String response;

    APIResponseObject(int responseCode,String response)
    {
         this.responseCode = responseCode;
         this.response = response;
    }
}

public class APIAccessTask extends AsyncTask<String,Void,APIResponseObject> {
    URL requestUrl;
    Context context;
    HttpURLConnection urlConnection;
    List<Pair<String,String>> postData, headerData;
    String method;
    int responseCode = HttpURLConnection.HTTP_OK;

    interface OnCompleteListener{
        void onComplete(APIResponseObject result);
    }

    public OnCompleteListener delegate = null;

    APIAccessTask(Context context, String requestUrl, String method, OnCompleteListener delegate){
        this.context = context;
        this.delegate = delegate;
        this.method = method;
        try {
            this.requestUrl = new URL(requestUrl);
        }
        catch(Exception ex){
            ex.printStackTrace();
        }
    }

    APIAccessTask(Context context, String requestUrl, String method, List<Pair<String,String>> postData, OnCompleteListener delegate){
        this(context, requestUrl, method, delegate);
        this.postData = postData;
    }

    APIAccessTask(Context context, String requestUrl, String method, List<Pair<String,String>> postData,
            List<Pair<String,String>> headerData, OnCompleteListener delegate ){
        this(context, requestUrl,method,postData,delegate);
        this.headerData = headerData;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected APIResponseObject doInBackground(String... params) {
        Log.d("debug", "url = "+ requestUrl);
        try {
            urlConnection = (HttpURLConnection) requestUrl.openConnection();

            if(headerData != null) {
                for (Pair pair : headerData) {
                    urlConnection.setRequestProperty(pair.first.toString(),pair.second.toString());
                }
            }

            urlConnection.setDoInput(true);
            urlConnection.setChunkedStreamingMode(0);
            urlConnection.setRequestMethod(method);
            urlConnection.connect();

            StringBuilder sb = new StringBuilder();

            if(!(method.equals("GET"))) {
                OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
                BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, "UTF-8"));
                writer.write(getPostDataString(postData));
                writer.flush();
                writer.close();
                out.close();
            }

            urlConnection.connect();
            responseCode = urlConnection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream in = new BufferedInputStream(urlConnection.getInputStream());
                BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
                String line;

                while ((line = reader.readLine()) != null) {
                    sb.append(line);
                }
            }

            return new APIResponseObject(responseCode, sb.toString());
        }
        catch(Exception ex){
            ex.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(APIResponseObject result) {
        delegate.onComplete(result);
        super.onPostExecute(result);
    }

    private String getPostDataString(List<Pair<String, String>> params) throws UnsupportedEncodingException {
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for(Pair<String,String> pair : params){
            if (first)
                first = false;
            else
                result.append("&");

            result.append(URLEncoder.encode(pair.first,"UTF-8"));
            result.append("=");
            result.append(URLEncoder.encode(pair.second, "UTF-8"));
        }
        return result.toString();
    }
}

class MainClass {
String url = "https://example.com./api/v1/ex";
String method = "POST";    
List<Pair<String,String>> postData = new ArrayList<>();

postData.add(new Pair<>("email","whatever");
postData.add(new Pair<>("password", "whatever");

new APIAccessTask(MainActivity.this, url, method, postData,
     new APIAccessTask.OnCompleteListener() {
 @Override
 public void onComplete(APIResponseObject result) {
     if (result.responseCode == HttpURLConnection.HTTP_OK) {
         String str = result.response;
         // Do your XML/JSON parsing here
     }
 }
}).execute();
}