I want to watch a directory for file changes. And I used WatchService in java.nio. I can successfully listen for file created event. But I can&#39;t listen for file modify event. I checked [official java tutorial][1], but still struggling.

Here is the source code.
    
    import static java.nio.file.LinkOption.NOFOLLOW_LINKS;
    import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
    import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
    import static java.nio.file.StandardWatchEventKinds.ENTRY_DELETE;
    import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
    
    import java.io.File;
    import java.io.IOException;
    import java.nio.file.FileSystem;
    import java.nio.file.Files;
    import java.nio.file.Path;
    import java.nio.file.WatchEvent;
    import java.nio.file.WatchEvent.Kind;
    import java.nio.file.WatchKey;
    import java.nio.file.WatchService;
    
    public class MainWatch {
    
    	public static void watchDirectoryPath(Path path) {
    		// Sanity check - Check if path is a folder
    		try {
    			Boolean isFolder = (Boolean) Files.getAttribute(path,
    					&quot;basic:isDirectory&quot;, NOFOLLOW_LINKS);
    			if (!isFolder) {
    				throw new IllegalArgumentException(&quot;Path: &quot; + path
    						+ &quot; is not a folder&quot;);
    			}
    		} catch (IOException ioe) {
    			// Folder does not exists
    			ioe.printStackTrace();
    		}
    
    		System.out.println(&quot;Watching path: &quot; + path);
    
    		// We obtain the file system of the Path
    		FileSystem fs = path.getFileSystem();
    
    		// We create the new WatchService using the new try() block
    		try (WatchService service = fs.newWatchService()) {
    
    			// We register the path to the service
    			// We watch for creation events
    			path.register(service, ENTRY_CREATE);
    			path.register(service, ENTRY_MODIFY);
    			path.register(service, ENTRY_DELETE);
    
    			// Start the infinite polling loop
    			WatchKey key = null;
    			while (true) {
    				key = service.take();
    
    				// Dequeueing events
    				Kind&lt;?&gt; kind = null;
    				for (WatchEvent&lt;?&gt; watchEvent : key.pollEvents()) {
    					// Get the type of the event
    					kind = watchEvent.kind();
    					if (OVERFLOW == kind) {
    						continue; // loop
    					} else if (ENTRY_CREATE == kind) {
    						// A new Path was created
    						Path newPath = ((WatchEvent&lt;Path&gt;) watchEvent)
    								.context();
    						// Output
    						System.out.println(&quot;New path created: &quot; + newPath);
    					} else if (ENTRY_MODIFY == kind) {
    						// modified
    						Path newPath = ((WatchEvent&lt;Path&gt;) watchEvent)
    								.context();
    						// Output
    						System.out.println(&quot;New path modified: &quot; + newPath);
    					}
    				}
    
    				if (!key.reset()) {
    					break; // loop
    				}
    			}
    
    		} catch (IOException ioe) {
    			ioe.printStackTrace();
    		} catch (InterruptedException ie) {
    			ie.printStackTrace();
    		}
    
    	}
    
    	public static void main(String[] args) throws IOException,
    			InterruptedException {
    		// Folder we are going to watch
    		// Path folder =
    		// Paths.get(System.getProperty(&quot;C:\\Users\\Isuru\\Downloads&quot;));
    		File dir = new File(&quot;C:\\Users\\Isuru\\Downloads&quot;);
    		watchDirectoryPath(dir.toPath());
    	}
        }


  [1]: http://docs.oracle.com/javase/tutorial/essential/io/notification.html

All java.nio.file Solutions on Gang of Coders

Total of 1 java.nio.file Solutions

Watching a Directory for Changes in Java