StAX Parser

Estimated study time: 13 minutes.

StAX (Streaming API for XML) is a pull-based parsing model that combines the memory efficiency of SAX with a simpler, more intuitive programming style — your code pulls the next event when it's ready, instead of reacting to callbacks.

Push vs Pull Parsing

• SAX (push) — the parser controls the flow, calling your callback methods as it encounters events.
• StAX (pull) — your code controls the flow, requesting the next event from the parser in a loop.

Example (Java)

XMLInputFactory factory = XMLInputFactory.newInstance();
XMLStreamReader reader = factory.createXMLStreamReader(new FileReader("course.xml"));

while (reader.hasNext()) {
    int event = reader.next();
    if (event == XMLStreamConstants.START_ELEMENT) {
        System.out.println("Start: " + reader.getLocalName());
    }
}

Why Choose StAX?

• Streams the document like SAX, so it scales well to large files.
• Easier to reason about than SAX's callback-driven style — code reads top-to-bottom.
• Supports both reading and writing XML streams.
• Lets you stop parsing early once you've found what you need.

StAX vs DOM vs SAX

Think of it as a spectrum: DOM trades memory for convenience, SAX trades convenience for memory efficiency, and StAX aims for a practical middle ground — memory-efficient like SAX, but easier to write and control like DOM.