WatchService - small code for monitoring folders

I'm very new to Java. I found and example of a folder watcher service that I wanted to use for a simple app but no matter what I do I cannot get it to work. As best as I can figure out is that I'm not assigning the path variable properly.

I'd also be very grateful if someone could explain why I have to specify the full java.nio.file.StandardWatchEventKind.ENTRY_CREATE even though I do the import at the beginning.

Code :

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import java.io.*;
import java.io.IOException;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.StandardWatchEventKind.*;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
 
public class FileWatcher {
	public static void main(String args[]) throws InterruptedException {	
 
FileSystem fs = FileSystems.getDefault();
WatchService watcher = null;
try {
	watcher = fs.newWatchService();
} catch (IOException ex) {
	System.err.println(ex);
}
Path dir = FileSystems.getDefault().getPath("H:\\Download");
System.out.println(dir.toString());
try {
    WatchKey key = dir.register(watcher, java.nio.file.StandardWatchEventKind.ENTRY_CREATE);
} catch (IOException x) {
    System.err.println(x);
}
for (;;) {
 
    //wait for key to be signaled
    WatchKey key = watcher.take();
 
 
    for (WatchEvent<?> event: key.pollEvents()) {
        WatchEvent.Kind<?> kind = event.kind();
 
        //The filename is the context of the event.
        WatchEvent<Path> ev = (WatchEvent<Path>)event;
        Path filename = ev.context();
        System.out.println(ev.kind() + " : " + ev.context());
    }
 
    //Reset the key -- this step is critical if you want to receive
    //further watch events. If the key is no longer valid, the directory
    //is inaccessible so exit the loop.
    boolean valid = key.reset();
    System.out.println(valid);
    if (!valid) {
        break;
    }
}
 
 
 
}
}

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what error does it show?

Use / instead of \\

I've changed the code now to the following and all the functionality that I wanted is in there and it works. The only problem I have with it is that it simply kind of freezes after a while (maybe an hour or so). I have no idea why. There are no error messages or anything like that, it just stops monitoring the folder. The frame still remains on the screen though.

Code java:

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import net.contentobjects.jnotify.JNotify;
import net.contentobjects.jnotify.JNotifyListener;
import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.awt.Dimension;
import java.awt.Toolkit;
 
import javax.swing.JTextArea;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import java.util.logging.*;
import java.awt.BorderLayout;
 
public class FileWatcher extends JPanel {
	// private static String line2 = "error";
	private JFrame frame = new JFrame();
	private JTextArea textArea = new JTextArea();
	private JScrollPane pane = new JScrollPane(textArea);
	private static FileWatcher watcher = new FileWatcher();
 
	// private String path;
	private void sample(String path) throws Exception {
		// System.out.println(path);
		showInfo("Monitoring: " + path);
		int mask = JNotify.FILE_CREATED | JNotify.FILE_DELETED
				| JNotify.FILE_MODIFIED | JNotify.FILE_RENAMED;
		boolean watchSubtree = true;
		int watchID = JNotify.addWatch(path, mask, watchSubtree, new Listener());
 
		Thread.sleep(1000000);		
 
                                boolean res = JNotify.removeWatch(watchID);
		if (!res) {
			// System.out.println("Invalid");
			showInfo("Invalid");
		}
	}
 
	public void TouchFile(String fName) {
		if ((fName.indexOf("Thumbs") == -1) && (fName.indexOf(".rar") == -1)
				&& (fName.indexOf(".part") == -1)) {
			String TodayDate = "";
			String fModifyDate = "";
			String line;
			String line2 = "error";
			Calendar calendar = Calendar.getInstance();
			SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
			File filename = new File(fName);
			try {
			} catch (Exception e) {
				e.printStackTrace();
			}
			TodayDate = dateFormat.format(calendar.getTime());
			fModifyDate = dateFormat.format(filename.lastModified());
			try {
				Thread.currentThread().sleep(1000);
				// showInfo(line2 + "  " + (!fModifyDate.equals(TodayDate)));
 
				while ((line2.indexOf("error") != -1)
						&& (!fModifyDate.equals(TodayDate))) {
					// System.out.println(fName + " modified on: " +
					// fModifyDate);
					line2 = " ";
					line = " ";
					Process p = Runtime.getRuntime().exec(
							"C:\\Users\\BLUE\\Documents\\MYDROP~1\\Utils\\WatchFolder\\touch.exe "
									+ "\"" + fName + "\"");
					// Process p = Runtime.getRuntime().exec("touch.exe " + "\""
					// + fName + "\"");
					BufferedReader input = new BufferedReader(
							new InputStreamReader(p.getInputStream()));
					while ((line = input.readLine()) != null) {
						line2 = line2 + "\n" + line;
					}
					input.close();
					// System.out.println(line2);
					p.waitFor();
					showInfo(line2);
				}
				showInfo(fName + " modified on: " + fModifyDate);
			} catch (Exception err) {
				err.printStackTrace();
			}
		}
	}
 
	public void showInfo(String data) {
		watcher.textArea.append(data + "\n");
		watcher.frame.getContentPane().validate();
		watcher.textArea.setCaretPosition(watcher.textArea.getText().length() - 1);
	}
 
	class Listener implements JNotifyListener {
		public void fileRenamed(int wd, String rootPath, String oldName,
				String newName) {
			// print("renamed " + rootPath + " : " + oldName + " -> " +
			// newName);
			showInfo("renamed " + rootPath + "\\" + oldName + " -> " + newName);
		}
 
		public void fileModified(int wd, String rootPath, String name) {
			// print("modified " + rootPath + " : " + name);
			TouchFile(rootPath + "\\" + name);
			// showInfo("modified " + rootPath + "\\" + name);
		}
 
		public void fileDeleted(int wd, String rootPath, String name) {
			// print("deleted " + rootPath + " : " + name);
			showInfo("deleted " + rootPath + "\\" + name);
		}
 
		public void fileCreated(int wd, String rootPath, String name) {
			// print("created " + rootPath + " : " + name);
			TouchFile(rootPath + "\\" + name);
			showInfo("created " + rootPath + "\\" + name);
		}
 
		void print(String msg) {
			// System.err.println(msg);
			showInfo(msg);
		}
	}
 
	public static void main(String[] args) {
		String path = "H:\\download";
		Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
		watcher.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		watcher.frame.setSize(500, 200);
		watcher.frame.setVisible(true);
		watcher.frame.getContentPane().add(watcher.pane);
		watcher.frame.setVisible(true);
		watcher.frame.setLocation(screenSize.width - 500,
				screenSize.height - 250);
		try {
			if (args.length > 0) {
				new FileWatcher().sample(args[0]);
			} else {
				new FileWatcher().sample(path);
 
			}
 
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

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I've found the following comment (for the Thread.sleep line of code) that I had deleted previously. Can someone explain to me what it means please. My application freezes regardless of this line of code but I think the key to why it does might lie here.

Code :

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// sleep a little, the application will exit if you         
// don't (watching is asynchronous), depending on your         
// application, this may not be required         
Thread.sleep(1000000);

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Quote:

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I've found the following comment (for the Thread.sleep line of code) that I had deleted previously. Can someone explain to me what it means please.

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See the API (Thread (Java Platform SE 6)), Threed.sleep causes the current thread to..well, sleep - stops the execution of the current thread. In this code above, for 1 million milliseconds.