The XMLStreamReader and XMLEventReader interfaces in Java's StAX (Streaming API for XML) API allow you to parse and process XML documents in a streaming fashion. The XMLStreamReader interface provides a lower-level API for parsing XML documents, while the XMLEventReader interface provides a higher-level, event-based API that allows you to process XML events as they occur.

Here's an example of using the XMLEventReader interface to read and process events from an XML document:

import javax.xml.stream.*;
import javax.xml.stream.events.*;

import java.io.*;

public class StAXExample {

    public static void main(String[] args) throws Exception {
        XMLInputFactory factory = XMLInputFactory.newInstance();
        XMLEventReader reader = factory.createXMLEventReader(new FileReader("example.xml"));
        while (reader.hasNext()) {
            XMLEvent event = reader.nextEvent();
            if (event.isStartElement()) {
                StartElement element = event.asStartElement();
                String name = element.getName().getLocalPart();
                System.out.println("Start element: " + name);
            } else if (event.isEndElement()) {
                EndElement element = event.asEndElement();
                String name = element.getName().getLocalPart();
                System.out.println("End element: " + name);
            } else if (event.isCharacters()) {
                Characters characters = event.asCharacters();
                String text = characters.getData();
                System.out.println("Text content: " + text);
            }
        }
        reader.close();
    }
}

In this example, we create an XMLInputFactory object, which is used to create an XMLEventReader object. We pass the name of the input XML file to the createXMLEventReader() method to create a new reader for that file. We then loop through the events in the document using the hasNext() and nextEvent() methods of the XMLEventReader interface. For each event, we check its type using the isStartElement(), isEndElement(), and isCharacters() methods, and then extract and process the relevant information.

In this case, we print out the name of each start element, the name of each end element, and the text content of any characters events.

Note that the XMLEventReader interface provides a higher-level, more convenient API for processing XML documents than the lower-level XMLStreamReader interface. However, it may be slightly slower and require more memory than the XMLStreamReader interface, depending on the specific requirements of your application.