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?

Solution 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();
    }
    ...
}

Solution 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).

Solution 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);
                }
            });

Comments

[Diablo.Wu]

There any other way? not use exception.

[Xiong Chiamiov]

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

[ashirley]

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 :-(

[David Bullock]

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').

[Panu Haaramo]

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

[Panu Haaramo]

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).

[Dmitry Trifonov]

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