The XMLOutputFactory is a factory class in Java's StAX (Streaming API for XML) API that creates instances of XMLStreamWriter, which is used to write XML documents in a streaming fashion. The XMLOutputFactory allows you to create XMLStreamWriter objects that can be used to write XML documents to various output destinations such as OutputStreams, Writers, and Files.

Here's an example of using the XMLOutputFactory to create an XMLStreamWriter and write an XML document to a file:

import javax.xml.stream.*;
import java.io.*;

public class StAXExample {

    public static void main(String[] args) throws Exception {
        OutputStream outputStream = new FileOutputStream("example.xml");
        XMLOutputFactory factory = XMLOutputFactory.newInstance();
        XMLStreamWriter writer = factory.createXMLStreamWriter(outputStream);
        writer.writeStartDocument();
        writer.writeStartElement("root");
        writer.writeStartElement("child");
        writer.writeAttribute("attribute", "value");
        writer.writeCharacters("text");
        writer.writeEndElement();
        writer.writeEndElement();
        writer.writeEndDocument();
        writer.close();
    }
}

In this example, we create an OutputStream object from an output file using a FileOutputStream. We then create an XMLOutputFactory object using the newInstance() method, which we use to create an XMLStreamWriter object by passing in the OutputStream object to the createXMLStreamWriter() method.

We then use the XMLStreamWriter to write the XML document by calling its various write methods, such as writeStartDocument(), writeStartElement(), writeAttribute(), writeCharacters(), and writeEndElement(). Finally, we close the writer using the close() method.

Note that the XMLStreamWriter interface provides a low-level, event-based API for writing XML documents, which may be more difficult to use than the higher-level, object-oriented DOM (Document Object Model) API or the SAX (Simple API for XML) API. However, StAX is generally more memory-efficient than the DOM API and faster than the SAX API for large documents, making it a good choice for certain types of applications.