WatchService无法在Java中注册

Question

i am doing a program for monitoring the file change in a folder, this is my reference link for my program. But unfortunately i am facing some error with my code

This is the error message show in my compiler

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    The method register(WatchService, WatchEvent.Kind<?>[], WatchEvent.Modifier...) in the type Path is not applicable for the arguments (WatchService, WatchEvent.Kind<Path>, WatchEvent.Kind<Path>, WatchEvent.Kind<Path>, Path)

This is my sample code

import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.HashMap;
import java.util.Map;

public class FileDetect {
    public static void main(String [] args)
    {
        try(WatchService svc = FileSystems.getDefault().newWatchService())
        {
            Map<WatchKey, Path> keyMap = new HashMap<>();
            Path path = Paths.get("files");
            keyMap.put(path.register(svc,
                    StandardWatchEventKinds.ENTRY_CREATE,
                    StandardWatchEventKinds.ENTRY_DELETE,
                    StandardWatchEventKinds.ENTRY_MODIFY,
                    path));

            WatchKey wk ;
            do 
            {
                wk = svc.take();
                Path dir = keyMap.get(wk);
                for(WatchEvent<?> event : wk.pollEvents())
                {
                    WatchEvent.Kind<?> type = event.kind();
                    Path fileName = (Path)event.context();
                    System.out.print(fileName);
                }
            }
            while(wk.reset());
        }
        catch(Exception e)
        {

        }

    }
}

I am get the error in my register method for the WatchService , i have search some link which i think the way i use the syntax should be correct.

Answer 1

I think you misplaced the parenthesis. Try this:

 keyMap.put(path.register(svc,
                          StandardWatchEventKinds.ENTRY_CREATE,
                          StandardWatchEventKinds.ENTRY_DELETE,
                          StandardWatchEventKinds.ENTRY_MODIFY),
            path);