Question

I’m using android’s SAX parser and I wish to stop processing after I have read N elements. Some of the feeds are quite large and can take a while to churn through. How can I stop parsing if certain conditions are met in the EndElementListener for a certain element? Here is my current listener

chanItem.setEndElementListener(new EndElementListener()  {
    public void end() {
        _items.add(_item);
        if (++_currentItem == _maxElements) {
                //BREAK OUT HERE
        }
    }
});

I’ve tried throwing an exception within end() but EndElementListener doesn’t allow for throwing any exceptions.
Guidance would be much appreciated.

Answer 1

Define a new unchecked exception called “SaxBreakOutException”:

class SaxBreakOutException extends RuntimeException {
}

Throw this in your listener:

chanItem.setEndElementListener(new EndElementListener()  {
    public void end() {
        _items.add(_item);
        if (++_currentItem == _maxElements) {
            throw new SaxBreakOutException();
        }
    }
});

And catch it in the code that calls XmLReader.parse():

reader.setContentHandler(handler);
try {
    reader.parse(new InputSource(new StringReader(xml)));
} catch (SaxBreakOutException allDone) {
}

Alternatively, switch to Android’s XmlPullParser which doesn’t require exceptions to break out early.