bejoy george bejoy george - 6 months ago 20
Android Question

How to fix android.os.NetworkOnMainThreadException?

In the below code I got an error when running my Android project for RssReader.

URL url = new URL(urlToRssFeed);
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
XMLReader xmlreader = parser.getXMLReader();
RssHandler theRSSHandler = new RssHandler();
xmlreader.setContentHandler(theRSSHandler);
InputSource is = new InputSource(url.openStream());
xmlreader.parse(is);
return theRSSHandler.getFeed();


And it shows an error:


android.os.NetworkOnMainThreadException


How can I fix this issue?

Answer

This exception is thrown when an application attempts to perform a networking operation on its main thread. Run your code in AsyncTask:

class RetrieveFeedTask extends AsyncTask<String, Void, RSSFeed> {

    private Exception exception;

    protected RSSFeed doInBackground(String... urls) {
        try {
            URL url= new URL(urls[0]);
            SAXParserFactory factory =SAXParserFactory.newInstance();
            SAXParser parser=factory.newSAXParser();
            XMLReader xmlreader=parser.getXMLReader();
            RssHandler theRSSHandler=new RssHandler();
            xmlreader.setContentHandler(theRSSHandler);
            InputSource is=new InputSource(url.openStream());
            xmlreader.parse(is);
            return theRSSHandler.getFeed();
        } catch (Exception e) {
            this.exception = e;
            return null;
        }
    }

    protected void onPostExecute(RSSFeed feed) {
        // TODO: check this.exception 
        // TODO: do something with the feed
    }
}

How to execute the task: In MainActivity.java file you can add this line within your oncreate() method

new RetrieveFeedTask().execute(urlToRssFeed);

Don't forget to add this to AndroidManifest.xml file:

<uses-permission android:name="android.permission.INTERNET"/>