Null pointer exception json parsing url android

Question

I am trying to parse a json entry from the url. Below is the code segment.

TextView txtViewParsedValue;
private JSONObject jsonObject;
private static String url = "https://www.dropbox.com/s/rhk01nqlyj5gixl/jsonparsing.txt?dl=1"; 
String strParsedValue = null;  
TextView txtViewParsedValue;
private JSONObject jsonObject;
private static String url = "https://www.dropbox.com/s/rhk01nqlyj5gixl/jsonparsing.txt?dl=1"; 
String strParsedValue = null;           

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    txtViewParsedValue = (TextView) findViewById(R.id.textview1);

    try {
        parseJSON();

    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

public void parseJSON() throws JSONException
{       
    JSONParser jParser = new JSONParser();
    jsonObject = jParser.getJSONFromUrl(url);

    JSONObject object = jsonObject.getJSONObject("student");

    JSONArray subArray = object.getJS ONArray("student");

    for(int i=0; i<subArray.length(); i++)
    {
        strParsedValue+="\n"+subArray.getJSONObject(i).getString("id").toString();
    }

    txtViewParsedValue.setText(strParsedValue);
}

I want to extract all id's of student and print them in textview. Its giving null pointer exception. Searched several posts relatng to this and tried them, but didn work, any guidance would be of great help!

ρяσѕρєя K · Accepted Answer · 2013-03-21 04:45:38Z

3

student is JsonArray instead of JsonObject but you are trying to get it as JsonObject. change your parsing code as :

JSONArray subArray =jsonObject.getJSONArray("student");//<<< get student JSONArray
for(int i=0; i<subArray.length(); i++)
  {
   strParsedValue+=
        "\n"+subArray.getJSONObject(i).getString("id").toString();
 }

answered Mar 21, 2013 at 4:45

ρяσѕρєя K

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3 Comments

bharath Over a year ago

Hi, it displays in the textview sometimes and remains blank sometimes on consecutive runs, my internet connections is good, any idea for this behavior??

ρяσѕρєя K Over a year ago

@bharath : use AsyncTask for getting data from Server which avoid freezing of UI when getting data from server

bharath Over a year ago

Thanks for the reply, any pointers for sample Async task to access the json data from server??

Rajitha Siriwardena · Accepted Answer · 2013-03-21 04:46:20Z

0

Dont use JSONObject object = jsonObject.getJSONObject("student"); because according to your JSON student is an array.

Change it to

JSONArray subArray = jsonObject.getJSONArray("student");

answered Mar 21, 2013 at 4:46

Rajitha Siriwardena

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