JAVA EXCEPTION THROW

public class ServerSend2 implements Runnable{
    public Thread thread;
    private ObjectOutputStream oos;
    private String user;
    private String dirpath;
    private Path dir;
    public ServerSend2(ObjectOutputStream oos, String user){
        this.oos = oos;
        this.user = user;
        dirpath = "/home/g0lem/Studium/Semester III/ProgPrak/system/db/"+user;
        dir = Paths.get(dirpath);
        thread = new Thread(this);
    }
    public void run(){
        start();
    }
    public void start(){
        try{

           WatchService watcher = FileSystems.getDefault().newWatchService();
           WatchKey key = dir.register(watcher,ENTRY_CREATE);
           while(oos != null){
            try {
                key = watcher.take();
            }
            catch (InterruptedException x) {
                return;
            }

            for (WatchEvent<?> event: key.pollEvents()) {
                WatchEvent.Kind<?> kind = event.kind();

                if (kind == OVERFLOW) {
                    continue;
                }
                WatchEvent<Path> ev = (WatchEvent<Path>)event;
                Path filename = ev.context();
                String t = filename.toString();
                FileInputStream fileStream = new FileInputStream(dirpath+"/"+t);
                ObjectInputStream ois = new ObjectInputStream(fileStream);
                Object toSend = ois.readObject();
                    oos.writeObject(toSend);
            }
        // Reset the key
            boolean valid = key.reset();
            if (!valid) {
            break;
            }
           }
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }
}