JSONObject return type

Question

The following android application code in Java outputs to:

[{"handle":"DmitriyH","firstName":"Dmitriy","lastName":"Khodyrev","country":"Russia","city":"Moscow","organization":"KL","contribution":122,"rank":"master","rating":2040,"maxRank":"international master","maxRating":2072,"lastOnlineTimeSeconds":1432130513,"registrationTimeSeconds":1268570311}]}

when extracting data from codeforces api- http://codeforces.com/api/user.info?handles=DmitriyH;

but I only want "firstName" of the user. Can anyone recommend changes to my code??

public class Http extends Activity {
   TextView httpStuff;
   HttpClient client;
   JSONObject json;
   final static String URL = http://codeforces.com/api/user.info?handles=;


@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.httpex);

    httpStuff = (TextView)findViewById(R.id.tvHttp);
    client = new DefaultHttpClient();
    new Read().execute("result");
}

public JSONObject lastSub(String username) throws ClientProtocolException, IOException, JSONException {
    StringBuilder url = new StringBuilder(URL);
    url.append(username);
    HttpGet get = new HttpGet(url.toString());

    HttpResponse r = client.execute(get);
    //httpStuff.setText("xxx");
    int status = r.getStatusLine().getStatusCode();
    if(status == 200) {
        HttpEntity e = r.getEntity();
        String data = EntityUtils.toString(e);
        JSONObject last = new JSONObject(data);

        return last;
    }
    else {
        Toast.makeText(Http.this, "error", Toast.LENGTH_SHORT);
        return null;

    }
}

public class Read extends AsyncTask <String, Integer, String> {

    @Override
    protected String doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        try {
            json = lastSub("avm12");
            return json.getString(arg0[0]);
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        httpStuff.setText(result);
    }

}

}

Solution

public JSONObject lastSub(String username) throws ClientProtocolException, IOException, JSONException {
StringBuilder url = new StringBuilder(URL);
url.append(username);
HttpGet get = new HttpGet(url.toString());

HttpResponse r = client.execute(get);
//httpStuff.setText("xxx");
int status = r.getStatusLine().getStatusCode();
if(status == 200) {
    HttpEntity e = r.getEntity();
    String data = EntityUtils.toString(e);
    JSONObject last = new JSONObject(data).getJSONArray("result").getJSONObject(0);

    return last;
}
else {
    Toast.makeText(Http.this, "error", Toast.LENGTH_SHORT);
    return null;

}
}

EDIT

Now suppose I am using the url "codeforces.com/api/user.status?handle=avm12"; and I want to extract the first ten( or say n number of them) "problem" tags. What should I do then?

Well first get the root JSONArray

JSONArray array= new JSONObject(data).getJSONArray("result");

Then in a for loop get all the needed JSONObjects

for(int k=0;k<n;k++){ // n must be less than array.length()
    JSONObject problemObject=array.getJSONObject(k).getJSONObject("problem");
   //do what you need to do with the problemObject E.G. Add them to an ArryList... 
}

Consider adding &count=N to your url to limit the output to the needed N results...

Comments

[Avinash]

Please explain the logic behind it.

[n1nsa1d00]

@Avinash supposing that arg0[0] parameter in this line json.getString(arg0[0]); is probably "firstName" and sice you asked for changes to your code I simply changed this line JSONObject last = new JSONObject(data); in your lastSub method to this JSONObject last = new JSONObject(data).getJSONArray("result").getJSONObject(0);

[Flaxie]

yeah but you used "user.status" instead of "user.info". "user.status" does not contain the field "firstName"

[Avinash]

Thanks a lot. I got it. This way we extract one of the several data. Now suppose I am using the url "codeforces.com/api/user.status?handle=avm12" and I want to extract the first ten( or say n number of them) "problem" tags. What should I do then?

[Avinash]

Thanx a lot marco. It was a great help. However, I got into another problem. Now that I have retrieved these data, I want to have http links behind them, (I mean make them clickable so that they open up a web page on being clicked). If you may help here. Thank you.

[n1nsa1d00]

Are you inflating any layout to display this data in your activity UI ?

[Avinash]

Nope. I was trying to do it using Array Adapter.

[n1nsa1d00]

Unless your're using a ListView there's no need to use ArrayAdapter.. Now do this : mark my answer as accepted and create a new question asking how to inflate a layout from a certain json response... and I will make sure to answer you with my solution otherwise someone else might do it it doesn't matter....