WatchService - cannot get this to work
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:
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 If the key is no longer valid, the directory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;
}
}
}
}
