Here is an example of how to use the FilteringParserDelegate class from the Apache Commons IO library:

import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.filefilter.IOFileFilter;
import org.apache.commons.io.filefilter.TrueFileFilter;
import org.apache.commons.io.monitor.FileAlterationMonitor;
import org.apache.commons.io.monitor.FileAlterationObserver;

import java.io.File;

public class Example {
    public static void main(String[] args) throws Exception {
        // Create a FileFilter that only accepts files ending with ".txt"
        IOFileFilter fileFilter = FileFilterUtils.suffixFileFilter(".txt");

        // Create a FileAlterationObserver that monitors a directory and its subdirectories
        FileAlterationObserver observer = new FileAlterationObserver("/path/to/directory", fileFilter);

        // Add a listener to the observer
        observer.addListener(new ExampleListener());

        // Create a FileAlterationMonitor with a polling interval of 1 second
        FileAlterationMonitor monitor = new FileAlterationMonitor(1000);

        // Add the observer to the monitor
        monitor.addObserver(observer);

        // Start the monitor
        monitor.start();
    }
}

In this example, the FilteringParserDelegate class is being used to filter files with the suffix ".txt" from the directory being monitored. The FileAlterationMonitor is then configured to monitor the specified directory and its subdirectories with a polling interval of 1 second. Once started, the monitor will notify the registered listener of any changes to the monitored files that match the specified file filter.