WebSocketServer и Timer Java

package model;

import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.util.HashSet;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;

import org.java_websocket.WebSocket;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.server.WebSocketServer;

public class video_chat_server extends WebSocketServer {
	private Set<WebSocket> conns;
	private int time_lesson;//время урока в минутах
	private int hour=0, min=0, sec=1;//тсавшееся время урока
	private Timer timer;
	
	public video_chat_server(int port, int time) throws UnknownHostException {
		super(new InetSocketAddress(port));
		conns = new HashSet<>();
		time_lesson=time;
		//устанавливаем время урока
		int num_min=0;
		int all_min=0;
		for(;;) {
			num_min=num_min+30;
			all_min=all_min+30;
			if(num_min==60) {
				hour++;
				num_min=0;
			}
			if(all_min>=time_lesson)break;
		}
		min=num_min;	
	}

	public video_chat_server( InetSocketAddress address ) {
		super(address);
	}

	@Override
	public void onClose(WebSocket conn, int arg1, String arg2, boolean arg3) {
		// TODO Auto-generated method stub
		System.out.println("CLOSESOCKET");
		conns.remove(conn);
	}

	@Override
	public void onError(WebSocket conn, Exception arg1) {
		// TODO Auto-generated method stub
		System.out.println("ERROR WEBSOCKET: "+arg1);
	}
	
	@Override
	public void onMessage(WebSocket conn, String message) {
		// TODO Auto-generated method stub
		System.out.println("Message from client " + conn.getRemoteSocketAddress().getAddress().getHostAddress() + ": " + message);
		AllSend(message);
	}

	@Override
	public void onOpen(WebSocket conn, ClientHandshake handshake) {
		// TODO Auto-generated method stub
		System.out.println("New connection from " + conn.getRemoteSocketAddress().getAddress().getHostAddress());
		if(conns.size()<2)conns.add(conn);
	}

	@Override
	public void onStart() {
		// TODO Auto-generated method stub
		System.out.println("STARTSOCKET");
		getTimeLesson();
	}
	
	//отправка всем сообщение
	public void AllSend(String message) {
		for (WebSocket sock : conns) {
            sock.send(message);
        }
	}
	
	public void getTimeLesson() {
		timer = new Timer();
		timer.scheduleAtFixedRate(new TimerTask() {
			@Override
			public void run() {
				String message;
				sec--;
				if(sec==-1) {
					sec=59;
					min--;
					if(min==-1) {
						if(hour>0) {
							min=59;
							hour--;
						}
					}
				}
				message="{\"oper\": \"TIMER\", \"data\": \"";
				if(hour>0)message+=Integer.toString(hour)+":";
				if(min>=0)message+=Integer.toString(min)+":";
				message+=Integer.toString(sec)+"\"}";
				AllSend(message);
	  		}
	  	}, 1000, 1000);
	}
}