How to stop parsing xml document with SAX at any time?

Question

I parse a big xml document with Sax, I want to stop parsing the document when some condition establish? How to do?

Kentledge

Answer 1

Create a specialization of a SAXException and throw it (you don't have to create your own specialization but it means you can specifically catch it yourself and treat other SAXExceptions as actual errors).

public class MySAXTerminatorException extends SAXException {
    ...
}

public void startElement (String namespaceUri, String localName,
                           String qualifiedName, Attributes attributes)
                        throws SAXException {
    if (someConditionOrOther) {
        throw new MySAXTerminatorException();
    }
    ...
}

Genera

There any other way? not use exception. – Kentledge

Why would you not want to? That's what exceptions are designed for. – Expostulation

fwiw, that isn't what exceptions are designed for. Terminating a parse like this is not an error condition. It is however the only way to do this afaict :-( – Matchbox

In fact, it should be SAXParseException so you can populate a Locator, and get a callback on the ErrorHandler (which is the right place to 'tidy up'). – Hemi

Here is good example - Stop a SAX parser when you have enough data – Vaccination

Answer 2

I am not aware of a mechanism to abort SAX parsing other than the exception throwing technique outlined by Tom. An alternative is to switch to using the StAX parser (see pull vs push).

Wingspan

Answer 3

I use a boolean variable "stopParse" to consume the listeners since i don´t like to use throw new SAXException();

private boolean stopParse;

article.getChild("title").setEndTextElementListener(new EndTextElementListener(){
            public void end(String body) {
                if(stopParse) {
                  return; //if stopParse is true consume the listener.
                }
                setTitle(body);
            }
        });

Update:

@PanuHaaramo, supossing to have this .xml

<root>
        <article>
               <title>Jorgesys</title>
        </article>
        <article>
               <title>Android</title>
        </article>
        <article>
               <title>Java</title>
        </article>
</root>

the parser to get the "title" value using android SAX must be:

   import android.sax.Element;
   import android.sax.EndTextElementListener;
   import android.sax.RootElement;
...
...
...
    RootElement root = new RootElement("root");
    Element article= root.getChild("article");
    article.getChild("title").setEndTextElementListener(new EndTextElementListener(){
                public void end(String body) {
                    if(stopParse) {
                      return; //if stopParse is true consume the listener.
                    }
                    setTitle(body);
                }
            });

Chiromancy

Is this for Android? I can only find android.sax.EndTextElementListener. Also what is article here? – Saulsauls

Thanks. I'm not developing for Android but clears it up! I guess this is then not doable in regular Java (which I'm using). – Saulsauls