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POJson parse from URL
 

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    <p>I am getting java.lang.NullPointerException when I run this. Does anyone know why this is happening and how I can fix it?</p> <p>Please take a look at my code and let me know if you have any suggestions.</p> <pre><code>{"begin":[{"id":1,"name":"Andy","size":1}],"open":[{"id":1,"name":"Tom","size":2}]} </code></pre> <p><strong>Fragment</strong></p> <pre><code>public class MainFragment extends Fragment { public MainFragment() {} //URL to get JSON Array private String url = "URL..."; //JSON Node Names private static final String TAG_BEGIN = "begin"; private static final String TAG_ID = "id"; private static final String TAG_NAME = "name"; private static final String TAG_SIZE = "size"; JSONArray begin = null; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); new JSONParse().execute(); return rootView; } private class JSONParse extends AsyncTask&lt;String, String, JSONObject&gt; { private ProgressDialog pDialog; @Override protected void onPreExecute() { super.onPreExecute(); pDialog = new ProgressDialog(HomeActivity.this); pDialog.setMessage("Getting Data ..."); pDialog.setIndeterminate(false); pDialog.setCancelable(true); pDialog.show(); } @Override protected JSONObject doInBackground(String... args) { JSONParser jParser = new JSONParser(); // Getting JSON from URL JSONObject json = jParser.getJSONFromUrl(url); return json; } @Override protected void onPostExecute(JSONObject json) { pDialog.dismiss(); try { // Getting JSON Array begin = json.getJSONArray(TAG_BEGIN); JSONObject c = begin.getJSONObject(0); // Storing JSON item in a Variable String id = c.getString(TAG_ID); String name = c.getString(TAG_NAME); String size = c.getString(TAG_SIZE); } catch (JSONException e) { e.printStackTrace(); } } } } </code></pre> <p><strong>JSONParser</strong></p> <pre><code>import android.util.Log; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONException; import org.json.JSONObject; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(String url) { // Making HTTP request try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } </code></pre> <p><strong>Error:</strong></p> <pre><code>E/JSON Parser﹕ Error parsing data org.json.JSONException: Value &lt;!DOCTYPE of type java.lang.String cannot be converted to JSONObject FATAL EXCEPTION: main java.lang.NullPointerException at ...$MainFragment$JSONParse.onPostExecute(MainActivity.java:399) at ...$MainFragment$JSONParse.onPostExecute(MainActivity.java:373) </code></pre> <p>Which is...</p> <pre><code>begin = json.getJSONArray(TAG_BEGIN); </code></pre> <p>and...</p> <pre><code>private class JSONParse extends AsyncTask&lt;String, String, JSONObject&gt; { </code></pre> <p><strong>EDIT (Answer)</strong></p> <p><strong>JSONParser</strong></p> <p>Inside of JSONParser I changed my code to this:</p> <pre><code>public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(String url) { // Making HTTP request try { DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); HttpUriRequest request = new HttpGet(url); request.setHeader("Accept", "application/json"); HttpResponse response = httpClient.execute(request); HttpEntity httpEntity = response.getEntity(); is = httpEntity.getContent(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } </code></pre> <p><strong>Inside of onPostExecute</strong></p> <pre><code>JSONArray begin = json.getJSONArray(TAG_BEGIN); for (int i = 0; i &lt; begin(); i++) { try { JSONObject b = = begin(i); String id = b.getString(TAG_ID); String name = b.getString(TAG_NAME); String size = b.getString(TAG_SIZE); } catch (JSONException e) { e.printStackTrace(); } } </code></pre>
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    1. COJust a side note. If you use Google Volley, it will help you alot!
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      1. USShervin Asgari
    2. COThanks for the tip. Do you know how to solve my problem without using Google Volley?
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    3. COYou code looks alright. I assume that your json object returned by doInBackground is null. Maybe no network connection?
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      1. UStiguchi
 

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