Question

i have an rss feed that comes via an XML. There are several events that are returned with information about them. The events are returned with tags…for eg: ….info…

as soon as i encounter tag, i want to update the listview that i am using to show the events.
So the user does not see the loading progress dialog, rather he sees the events getting added to a list.
How do i do this.

thank you in advance.

Answer 1

Here’s pseudo codeish example for one way of doing this using SAX parser;

// MyParserThread is assumed to be inner class of Activity here.
private class MyParserThread extends Thread implements MyParserObserver {
    private MyParser mParser;
    public MyParserThread() {
       mParser = new MyParser();
       mParser.setObserver(this);
    }
    public void run() {
        try {
            // load xml
            mParser.parse(xml);
        } catch (Exception ex) {
        }
    }
    public void onMyParserEvent(final DataReceivedFromParsing data) {
        runOnUiThread(new Runnable() {
            public void run() {
                 // update data to your UI.
            }
        });
    }
    public void cancel() {
        mParser.cancel();
    }
}

And in your parser you’re implementing ContentHandler

public void cancel() {
    mCancelled = true;
}
public void startElement(....) {
    if (mCancelled) {
        // If you want to stop Thread from running, all you have to do
        // is make parsing stop.
        throw new SAXException("Cancelled");
    }
    ....
}

And triggering parsing once your onCreate is called would be;

public void onCreate(...) {
    ...
    mParserThread = new MyParserThread();
    mParserThread.start();
    ...
}

Now this isn’t perfect but hopefully gives some idea how to do Thread handling for this purpose. Fundamentally you just have start it, and adding ‘cancel’ functionality is somewhat more of a bonus – e.g. for cases in which Activity is destroyed while your Thread is running.