Address aleardy in use exception（Multicast Socket）

我試圖寫服務器和客戶端的服務，它會告訴當前時間。我的代碼：Address aleardy in use exception（Multicast Socket）

服務器

public class TimeServer { 

    public static void main(String[] args) { 
     try { 
     final DatagramSocket so = new DatagramSocket(8189); 
     new Thread(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        while (true) { 
        try { 
         InetAddress group = InetAddress.getByName("200.20.2.0"); 
         byte[] buf = new byte[256]; 
         Calendar cal = Calendar.getInstance(); 
         buf = cal.toString().getBytes(); 
         DatagramPacket packet = new DatagramPacket(buf, buf.length, 
           group, 8189); 
         so.send(packet); 
        } catch (IOException ex) { 
         ex.printStackTrace(); 
        } 
        Thread.sleep((int)(Math.random() * 5)); 
        } 
       } catch (InterruptedException ex) { 
        ex.printStackTrace(); 
       } 
      } 
     }).start(); 
     } catch (IOException ex) { 
     ex.printStackTrace(); 
     } 
    } 
}

CLIENT

public class TimeClient { 

    public static void main(String[] args) { 
     try { 
     MulticastSocket so = new MulticastSocket(8190); 
     InetAddress group = InetAddress.getByName("200.20.2.0"); 
     so.joinGroup(group); 

     //5 razy czekamy na otrzymanie od serwera wiadomosci 
     for (int a=0; a<5; a++) { 
      byte[] buf = new byte[256]; 
      DatagramPacket packet = new DatagramPacket(buf, buf.length); 
      so.receive(packet); 

      String recv = new String(packet.getData()); 
      System.out.println("RECEIVED: " + recv); 
     } 

     so.leaveGroup(group); 
     so.close(); 
     } catch (IOException ex) { 
     ex.printStackTrace(); 
     } 
    } 

}

當啓動服務器，然後客戶端，我得到以下錯誤：

java.net.BindException: Address already in use 
    at java.net.PlainDatagramSocketImpl.bind0(Native Method) 
    at java.net.AbstractPlainDatagramSocketImpl.bind(AbstractPlainDatagramSocketImpl.java:95) 
    at java.net.DatagramSocket.bind(DatagramSocket.java:376) 
    at java.net.MulticastSocket.<init>(MulticastSocket.java:172) 
    at java.net.MulticastSocket.<init>(MulticastSocket.java:137) 
    at timeclient.TimeClient.main(TimeClient.java:13)

請幫幫忙，謝謝

編輯： 我改變了客戶端端口，現在我得到異常：

java.net.SocketException: Not a multicast address 
    at java.net.MulticastSocket.joinGroup(MulticastSocket.java:306) 
    at timeclient.TimeClient.main(TimeClient.java:15)

現在是什麼？

來源

2013-04-06 user2250795