Android HttpurlConnection read data using BufferedReader but get null value after append it to a StringBuilder

Question

I got data from reader.readLine(). But it doesn't enter the while loop. The return 'json' string is null.

Someone please help me to solve the issue. i have already tried a lot for a correct solution.

try {            
    URL urL = new URL(url);
    urlConnection = (HttpURLConnection) urL.openConnection();
    urlConnection.setRequestMethod("POST");
    urlConnection.addRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    urlConnection.addRequestProperty("Accept", "application/json");
    urlConnection.setConnectTimeout(10000);
    urlConnection.setReadTimeout(15000);
    urlConnection.setDoInput(true);
    urlConnection.setDoOutput(true);
    Uri.Builder builder = new Uri.Builder()
            .appendQueryParameter("PackageName", packagename);

    String query = builder.build().getEncodedQuery();

    OutputStream os = urlConnection.getOutputStream();
    BufferedWriter writer = new BufferedWriter(
            new OutputStreamWriter(os, "UTF-8"));
    writer.write(query);
    writer.flush();
    writer.close();
    os.close();

    urlConnection.connect();

    InputStream in = new BufferedInputStream(urlConnection.getInputStream());

    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    StringBuffer result = new StringBuffer();

    Log.e("READER","....."+reader.readLine());
    String line=reader.readLine();
    while (line != null) {
        result.append(line).append('\n');
    }
    json=result.toString();
    in.close();

} catch (Exception e) {
    e.printStackTrace();
} finally {
    urlConnection.disconnect();
}
Log.e("RESULT","...."+json);
return json;

I think your code includes `try {` ___ look just above the code snippet you shared ___ — Rafaf Tahsin, Sep 27 '16 at 08:59
Atlast I got it. The issue was on the line Log.e("READER","....."+reader.readLine()); String line=reader.readLine(); I changed the above lines as String line=reader.readLine(); Log.e("READER","....."+line); Now its working fine... Thank you all for the support..:) — Aparna.M, Sep 27 '16 at 10:28

K Neeraj Lal · Answer 1 · 2016-09-27T11:36:13.760

1

Remove the extra reader.readLine() in the log,

Log.e("READER","....." + reader.readLine());

Try this code,

Log.e("ResponseCode", "" + urlConnection.getResponseCode());

InputStream in = new BufferedInputStream(urlConnection.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuffer result = new StringBuffer();

String line;
while ((line = reader.readLine()) != null) {
    result.append(line);
}
json = result.toString();
in.close();

edited Sep 27 '16 at 11:36

answered Sep 27 '16 at 08:43

K Neeraj Lal

6,768
3
24
33

Thank You for the suggestion. I have already do the same. But still the same problem. :( – Aparna.M Sep 27 '16 at 08:48
Make sure you are getting data from the API. Try it in the browser. – K Neeraj Lal Sep 27 '16 at 08:50
Yes, the data is getting from API – Aparna.M Sep 27 '16 at 08:57
it does'nt enter the while ((line = reader.readLine()) != null) loop – Aparna.M Sep 27 '16 at 09:10

score 0 · Answer 2 · answered Sep 27 '16 at 08:53

0

Do this it's basic maybe you missed it :

   json=result.toString();
    in.close();

} catch (Exception e) {
    e.printStackTrace();
} finally {
    urlConnection.disconnect();
}
Log.e("RESULT","...."+json);
if (json!=null)
return json;

It will skip null pointer exception:

answered Sep 27 '16 at 08:53

DevKRos

422
2
15

No, it's not solving my issue – Aparna.M Sep 27 '16 at 09:05

score 0 · Answer 3 · answered Sep 27 '16 at 09:36

If all you are doing is downloading a jsonString from the API, this should sort you out:

String jsonString = "";

    try {

        URL mURL = new URL(yourURL);

        HttpURLConnection mHttpURLConnection;
        mHttpURLConnection = (HttpURLConnection)mURL.openConnection();

        mHttpURLConnection.setDoInput(true);

        mHttpURLConnection.connect();

        InputStream mInputStream = mHttpURLConnection.getInputStream();

        int i = 0;
        while ((i = mInputStream.read()) != -1) {
            jsonString += (char) i;
        }

    } catch (MalformedURLException e) {
        e.printStackTrace();

    } catch (IOException e) {
        e.printStackTrace();

    }
Log.e("JSON","Json String received: " + jsonString);

Android HttpurlConnection read data using BufferedReader but get null value after append it to a StringBuilder

3 Answers3