How do I call REST API from an android app?-ThrowExceptions

Exception or error:

I’m new to android and new to programming as well. How do I call a REST api (GET/POST request) from an android app. Please suggest me a good tutorial, or give me an idea to start with.

How to solve:
  1. If you want to integrate Retrofit (all steps defined here):

Goto my blog : retrofit with kotline

  1. Please use android-async-http library.

the link below explains everything step by step.

http://loopj.com/android-async-http/

Here are sample apps:

  1. http://www.techrepublic.com/blog/software-engineer/calling-restful-services-from-your-android-app/

  2. http://blog.strikeiron.com/bid/73189/Integrate-a-REST-API-into-Android-Application-in-less-than-15-minutes

Create a class :

public class HttpUtils {
  private static final String BASE_URL = "http://api.twitter.com/1/";

  private static AsyncHttpClient client = new AsyncHttpClient();

  public static void get(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
      client.get(getAbsoluteUrl(url), params, responseHandler);
  }

  public static void post(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
      client.post(getAbsoluteUrl(url), params, responseHandler);
  }

  public static void getByUrl(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
      client.get(url, params, responseHandler);
  }

  public static void postByUrl(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
      client.post(url, params, responseHandler);
  }

  private static String getAbsoluteUrl(String relativeUrl) {
      return BASE_URL + relativeUrl;
  }
}

Call Method :

    RequestParams rp = new RequestParams();
    rp.add("username", "aaa"); rp.add("password", "aaa@123");

    HttpUtils.post(AppConstant.URL_FEED, rp, new JsonHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
            // If the response is JSONObject instead of expected JSONArray
            Log.d("asd", "---------------- this is response : " + response);
            try {
                JSONObject serverResp = new JSONObject(response.toString());                                                
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }                   
        }

        @Override
        public void onSuccess(int statusCode, Header[] headers, JSONArray timeline) {
            // Pull out the first event on the public timeline

        }
    });

Please grant internet permission in your manifest file.

 <uses-permission android:name="android.permission.INTERNET" />

you can add compile 'com.loopj.android:android-async-http:1.4.9' for Header[] and compile 'org.json:json:20160212' for JSONObject in build.gradle file if required.

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