Parse Exception: At line 1, column 0: no element found

Question

I have a weird issue. I receive the following error that causes a force-close:

org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 0: no element found at org.apache.harmony.xml.ExpatParser.parseFragment(ExpatParser.java:508) at org.apache.harmony.xml.ExpatParser.parseDocument(ExpatParser.java:467) at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:329) at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:286)

After clicking the Force Close button, the Activity is recreated and the parsing completes without a hitch. I'm using the following code snippet inside doInBackground of an AsyncTask:

URL serverAddress = new URL(url[0]);

HttpURLConnection connection = (HttpURLConnection) serverAddress.openConnection();
connection.setRequestMethod("GET");
connection.setDoOutput(true);
connection.setReadTimeout(10000);
connection.connect();

InputStream stream = connection.getInputStream();

SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();

XMLReader xr = sp.getXMLReader();

xr.parse(new InputSource(stream));  // The line that throws the exception

Why would the Activity force-close and then run without any problems immediately after? Would a BufferedInputStream be any different? I'm baffled. :(

Thanks for your time everyone.

Update: It turns out HttpURLConnection.getResponseCode() returns -1 every so often, so the InputStream probably isn't being correctly set.

Solution 1

HTTPURLConnection connection = (HttpURLConnection) serverAddress.openConnection();
connection.setRequestMethod("GET");
connection.setDoOutput(true);

Those lines are a bit odd. Is it HTTPURLConnection or HttpURLConnection? The default request method is already GET. The setDoOutput(true) will however force it to POST.

I'd replace all of those lines by

URLConnection connection = serverAddress.openConnection();

and retry. It might happen that it returned an error because you forced POST and didn't write anything to the output (the request body). The connection.connect() is by the way already implicitly called by connection.getInputStream(), so that line is superfluous as well.

Update: does the following for testing purposes work?

BufferedReader reader = new BufferedReader(new InputStreamReader(stream, "UTF-8"));
for (String line; (line = reader.readLine()) != null;) {
    System.out.println(line);
}
reader.close();

Solution 2

I dont' know if you fixed this, but I had the same problem. It was weird, it would work fine in the emulator, but then on the phone, it was always giving me the xr.parse() error. Even when I printed the InputStream it would give me legitimate output of the xml document. It seemed the problem was in the creating of the InputSource object

Here's how I fixed it: instead of using InputStream to create your InputSource I just created input source from the url string directly.

InputSource a =  new InputSource(url_string);   

where url_string is just a string with your url. Don't ask me why it works...I dont really like it, as there's no way to check for timeouts and things like that it seems. But it works, let me know how it goes!

Solution 3

Even I faced the same issue. I was first using the InputStream in Scanner to print the content of it. And then trying to pass it in XML parser.

The problem was that I was not closing the Scanner object. And using the Inputstream in parser.

After closing the scanner object, I was able to tackle this issue.

Solution 4

Per InputStream javadoc the method will block until the data is available or the EOF is encountered. So, the other side of Socket needs to close it - then the inStream.read() call will return.

If you use BufferedReader , you can read in a line-by-line manner. The readLine() method will return as soon as a line from HTTP response is read.

Solution 5

On a related design note, loading up contents of a URL should never Force Close an activity - I recommend putting all this into an AsyncTask implementation and report or retry after you are back on the GUI thread.

View more solutions

Comments

[Jonathan Holloway]

Looks like the stream is null, can you dump the contents of it to System.out.println with commons IOUtils?

[BalusC]

Is this a copypaste? HTTPURLConnection != HttpURLConnection.

[jeffh]

That was a typo, HttpURLConnection fixed. Sorry about that.

[jeffh]

Thanks BalusC, extremely informative. Will make the changes and give it a shot. What is interesting, is that most of the time the XML parses without a hitch. It's almost a luck of the draw to have an exception thrown...though it seems to happen frequently enough to be a problem.

[jeffh]

Thank you ring bearer, will look into this further.

[jeffh]

Agreed. The code snippet in the original post resides in doInBackground of an AsyncTask.

[jeffh]

After making the changes, the force-close behavior still exists. It seems like the parser isn't parsing anything. Hooking up with the debugger to get to the bottom of this.

[jeffh]

Regarding the update, that should work, but I think System.util.Log is utilized instead of System.out in Android. Will test and update the original post. Thanks!

[jeffh]

Thanks for your response. I don't think it will work specifically for my case, because I need to use HttpURLConnection.setRequestProperty(). I've temporarily fixed the issue by checking the response code and retrying the connection if the code is -1. Your input may help others though!