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POAndroid asynctask exception
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copied!<p>i'm doing an app that have to get an XML file from an url and parse it. I always find this log cat (PS:i can't find the correct google prettify sintax code highlighting): </p> <pre><code>11-06 23:12:44.940: E/Trace(8751): error opening trace file: No such file or directory(2) 11-06 23:12:51.345: E/Error:(8751): expected: /hr read: body (position:END_TAG </body>@6:8 in java.io.StringReader@431887b8) 11-06 23:12:51.360: E/AndroidRuntime(8751): FATAL EXCEPTION: AsyncTask #1 11-06 23:12:51.360: E/AndroidRuntime(8751): java.lang.RuntimeException: An error occured while executing doInBackground() 11-06 23:12:51.360: E/AndroidRuntime(8751): at android.os.AsyncTask$3.done(AsyncTask.java:299) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.FutureTask.setException(FutureTask.java:124) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.FutureTask.run(FutureTask.java:137) 11-06 23:12:51.360: E/AndroidRuntime(8751): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.lang.Thread.run(Thread.java:856) 11-06 23:12:51.360: E/AndroidRuntime(8751): Caused by: java.lang.NullPointerException 11-06 23:12:51.360: E/AndroidRuntime(8751): at com.ambro.app.Update$connection.doInBackground(Update.java:39) 11-06 23:12:51.360: E/AndroidRuntime(8751): at com.ambro.app.Update$connection.doInBackground(Update.java:1) 11-06 23:12:51.360: E/AndroidRuntime(8751): at android.os.AsyncTask$2.call(AsyncTask.java:287) 11-06 23:12:51.360: E/AndroidRuntime(8751): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305) 11-06 23:12:51.360: E/AndroidRuntime(8751): ... 5 more </code></pre> <p>the xml could be found at: <a href="http://www.lookedpath.tk/apps/firstapp/version.xml" rel="nofollow">http://www.lookedpath.tk/apps/firstapp/version.xml</a></p> <p>the update.java code: </p> <pre class="lang-java prettyprint-override"><code>public class Update extends Activity { private TextView testo2; @Override public void onCreate(Bundle savedInstanceState) { setContentView(R.layout.update); super.onCreate(savedInstanceState); testo2= (TextView) findViewById(R.id.textView2); } public void goToUpdate (View view) { System.out.println("ciao"); new connection().execute(); } public class connection extends AsyncTask<Void, Void, Boolean> { protected Boolean doInBackground(Void... params) { boolean updated=false; String lastversion=null; Element e=null; final String URL = "http://www.lookedpath.tk/apps/firstapp/version.xml"; final String VERSION = "version"; final String APPLICATION = "application"; XMLParser parser = new XMLParser(); String xml = parser.getXmlFromUrl(URL); // getting XML Document doc = parser.getDomElement(xml); // getting DOM element NodeList nl = doc.getElementsByTagName(APPLICATION); for (int i=0;i<nl.getLength();i++) { e = (Element) nl.item(0); lastversion = parser.getValue(e, VERSION); // name child value } String actver = getString(R.string.version); if(actver==lastversion) updated=true; return updated; } protected void onPostExecute(Boolean... result) { if(result[0]==false){ testo2.setText(R.string.newversion); } else { testo2.setText(R.string.nonewversion); } } }; } </code></pre> <p>so this is the xmlparser.java file:</p> <pre class="lang-java prettyprint-override"><code>public class XMLParser { public String getXmlFromUrl(String url) { String xml = null; try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); xml = EntityUtils.toString(httpEntity); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } // return XML return xml; } public Document getDomElement(String xml){ Document doc = null; DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder db = dbf.newDocumentBuilder(); InputSource is = new InputSource(); is.setCharacterStream(new StringReader(xml)); doc = db.parse(is); } catch (ParserConfigurationException e) { Log.e("Error: ", e.getMessage()); return null; } catch (SAXException e) { Log.e("Error: ", e.getMessage()); return null; } catch (IOException e) { Log.e("Error: ", e.getMessage()); return null; } // return DOM return doc; } public String getValue(Element item, String str) { NodeList n = item.getElementsByTagName(str); return this.getElementValue(n.item(0)); } public final String getElementValue( Node elem ) { Node child; if( elem != null){ if (elem.hasChildNodes()){ for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){ if( child.getNodeType() == Node.TEXT_NODE ){ return child.getNodeValue(); } } } } return ""; } } </code></pre> <p>the logcat say that the error is in the line 39 of the update class:</p> <pre class="lang-java prettyprint-override"><code>NodeList nl = doc.getElementsByTagName(APPLICATION); </code></pre> <p>but i can't manage to resolve the problem. can anyone help me?</p> <p><strong>UPDATE:</strong> i have fixed the error 405 but i still have a null pointer exception. i found that the program run correctly but never enter in the post execute method because of this exception..</p>

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