How should I handle HTTP response codes when using AsyncTask?

Question

I am creating an Android application that takes user input, tries to connect to the API URL with the specified input and retrieve the data and display it. Now I was able to do everything above, but there is a potential chance that if the user enters something, and he does not exist, my application will fail due to NPE (Null Pointer exception).

The API that I use shows me a list of response errors that may occur, but I'm not sure how I should handle or implement a function that takes into account these response errors.

Currently, my AsyncTask extended class has the following parameters: String, Void, JSONObject , and the following code is what I have in my doInBackground method .

URL url = new URL(params[0]);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();

int statusCode = urlConnection.getResponseCode();
switch (statusCode) {
    case 400:
    return "Error 400 - Bad request.";
    case 401:
    return "Error 401 - Unauthorized request.";
}

I cannot return a String because my AsyncTask parameter returns a JSONObject. I can change it so that it returns a string, but I believe that this is not the right logical way to handle response errors.

Now, if the API response code was 404 (no data found), I do not want the application to crash because it cannot return a JSONObject, instead I would like it to continue moving on to the next fragment and display the minimum information.

So, how do I handle error response handling when my method returns a JSONObject?

Answer 1

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Answer 2

null, statusCode 200:

            URL url = new URL(params[0]);
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            int statusCode = urlConnection.getResponseCode();

            if(statusCode!= 200){

                return null;

            }

postExecute :

protected void onPostExecute(JSONObject result) {

    if (result == null) {

        // Inform the user something weird happened

    }
    else{

        // Do your normal condition with your JSON object
    }

: JSON ArrayList:

            ArrayList<Object>  result = new ArrayList<Object>();

            URL url = new URL(params[0]);
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            int statusCode = urlConnection.getResponseCode();


            switch (statusCode) {

                case 200:
                   // Your code to build your JSON object
                   JSONObject yourJsonObject = ...
                   result.add("Ok");
                   result.add(yourJsonObject);
                   break;
                case 400:
                   result.add("Error 400 - Bad request.");
                   result.add(null);
                   break;
                case 401:
                   result.add("Error 401 - Unauthorized request.");
                   result.add(null);
                   break;
            }

postExecute , ArrayList:

protected void onPostExecute(ArrayList<Object> result) {

    String message = (String) result.get(0);
    JSONObject yourJsonObject = (JSONObject) result.get(1);


    if (result == yourJsonObject) {

        // Inform the user something weird happened
        // Example: Toast the message

    }
    else{

        // Do your normal condition with your JSON object

    }