null pointer exception on getNodeValue() when parsing XML web page - android
Question
I looked over several of the answers posted here, but I can't find the answer I need. It may have to do with the web site itself, but I don't think it is. I'm trying to parse an XML on a web site and I'm getting a null pointer exception error.
I run the parsing is a separate thread following Google demand when reading from the web.
please see my code and try to help.
class BackgroundTask1 extends AsyncTask<String, Void, String[]> {
protected String[] doInBackground(String... url) {
new HttpGet();
new StringBuffer();
InputStream is = null;
HttpURLConnection con = null;
try {
//Log.d("eyal", "URL: " + boiUrl);
URL url1 = new URL("http://www.boi.org.il/currency.xml");
con = (HttpURLConnection)url1.openConnection();
con.setRequestMethod("GET");
con.connect();
is = con.getInputStream();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(is);
NodeList lastVld = doc.getElementsByTagName("LAST_UPDATE");
String lastV = lastVld.item(0).getFirstChild().getNodeValue();
}
catch (Exception e) {
e.printStackTrace();
}
I get the error on the last line.
Thanks for your help.
3 answers
solution1
0 2014-07-15 17:47:19
You only have one LAST_UPDATE tag in your xml and it has an inner value, so try just using the node value from the Node Class you get from item(0)
String lastV = lastVld.item(0).getNodeValue();
HTHs
solution2
0 2014-07-15 17:48:56
There is no node returned for that tag name. You may want to first check the size of the lastVld and then try to access the items in there.
solution3
0 ACCPTED 2014-07-16 06:26:33
This code worked for me
InputStream is = null;
HttpURLConnection con = null;
try {
URL url1 = new URL("http://www.boi.org.il/currency.xml");
con = (HttpURLConnection)url1.openConnection();
con.setRequestMethod("GET");
con.connect();
is = con.getInputStream();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(is);
NodeList lastVld = doc.getElementsByTagName("LAST_UPDATE");
Element elem = (Element) lastVld.item(0);
String lastV = elem.getTextContent();
System.out.println(lastV);
} catch (Exception e) {
e.printStackTrace();
}
I verified I was getting good content by adding a transformer to print out the results to the console.
TransformerFactory tFactory = TransformerFactory.newInstance();
Transformer xform = tFactory.newTransformer();
xform.transform(new DOMSource(doc), new StreamResult(System.out));
There was a couple times I tried running where elem came out null, which I think had something to do with some bad content being retrieved from the URL. This was the content that was printed by the transformer.
<html>
<body>
<script>document.cookie='iiiiiii=11a887d6iiiiiii_11a887d6; path=/';window.location.href=window.location.href;</script>
</body>
</html>
I noticed that if I had this file open in my browser, the code would all of a sudden quit working until I refreshed the page, then it started giving me the right output.
I suspect there's an issue with something at this URL, because when it works properly, this code works fine.
Good luck...
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