From http://javaevangelist.blogspot.com/2013/09/apache-commons-io-file-monitoring.html

FileAlterationListenerImpl.java

package com.bluelotussoftware.commons.io;

import java.io.File;
import java.util.Date;
import org.apache.commons.io.monitor.FileAlterationListener;
import org.apache.commons.io.monitor.FileAlterationObserver;

/**
 *
 * @author John Yeary
 * @version 1.0
 */
public class FileAlterationListenerImpl implements FileAlterationListener {

    /**
     * {@inheritDoc}
     */
    @Override
    public void onStart(final FileAlterationObserver observer) {
        System.out.println("The WindowsFileListener has started on " + observer.getDirectory().getAbsolutePath());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onDirectoryCreate(final File directory) {
        System.out.println(directory.getAbsolutePath() + " was created.");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onDirectoryChange(final File directory) {
        System.out.println(directory.getAbsolutePath() + " wa modified");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onDirectoryDelete(final File directory) {
        System.out.println(directory.getAbsolutePath() + " was deleted.");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onFileCreate(final File file) {
        System.out.println(file.getAbsoluteFile() + " was created.");
        System.out.println("----------> length: " + file.length());
        System.out.println("----------> last modified: " + new Date(file.lastModified()));
        System.out.println("----------> readable: " + file.canRead());
        System.out.println("----------> writable: " + file.canWrite());
        System.out.println("----------> executable: " + file.canExecute());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onFileChange(final File file) {
        System.out.println(file.getAbsoluteFile() + " was modified.");
        System.out.println("----------> length: " + file.length());
        System.out.println("----------> last modified: " + new Date(file.lastModified()));
        System.out.println("----------> readable: " + file.canRead());
        System.out.println("----------> writable: " + file.canWrite());
        System.out.println("----------> executable: " + file.canExecute());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onFileDelete(final File file) {
        System.out.println(file.getAbsoluteFile() + " was deleted.");
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void onStop(final FileAlterationObserver observer) {
        System.out.println("The WindowsFileListener has stopped on " + observer.getDirectory().getAbsolutePath());
    }
}

FileMonitor.java

package com.bluelotussoftware.commons.io;

import java.io.File;
import org.apache.commons.io.monitor.FileAlterationMonitor;
import org.apache.commons.io.monitor.FileAlterationObserver;

/**
 *
 * @author John Yeary
 * @version 1.0
 */
public class FileMonitor {

    public static void main(String[] args) throws Exception {

        // Change this to match the environment you want to watch.
        final File directory = new File("/Users/jyeary/Desktop");
        FileAlterationObserver fao = new FileAlterationObserver(directory);
        fao.addListener(new FileAlterationListenerImpl());
        final FileAlterationMonitor monitor = new FileAlterationMonitor();
        monitor.addObserver(fao);
        System.out.println("Starting monitor. CTRL+C to stop.");
        monitor.start();

        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    System.out.println("Stopping monitor.");
                    monitor.stop();
                } catch (Exception ignored) {
                }
            }
        }));
    }
}