Java UDP中的空指针异常

这是我的主要方法：

public void broadcastName(final String name, final InetAddress broadcastIP) {
    // Broadcasts the name of the device at a regular interval
    System.out.println("Broadcasting started!");
    Thread broadcastThread = new Thread(new Runnable() {

        @Override
        public void run() {
            try {
                String request = "ADD:"+name;
                byte[] message = request.getBytes();
                DatagramSocket socket = new DatagramSocket();
                socket.setBroadcast(true);
                DatagramPacket packet = new DatagramPacket(message, message.length, broadcastIP, BROADCAST_PORT);
                while(BROADCAST) {
                    System.out.println("socket: "+socket);
                    socket.send(packet);
                    System.out.println("Broadcast packet sent: " + packet.getAddress().toString());
                    Thread.sleep(BROADCAST_INTERVAL);
                }
                System.out.println("Broadcaster ending!");
                socket.disconnect();
                socket.close();
                return;
            }
            catch(SocketException e) {
                System.out.println("SocketException in broadcast: " + e);
                System.out.println("Broadcaster ending!");
                return;
            }
            catch(IOException e) {
                System.out.println("IOException in broadcast: " + e);
                System.out.println("Broadcaster ending!");
                return;
            }
            catch(InterruptedException e) {
                System.out.println("InterruptedException in broadcast: " + e);
                System.out.println("Broadcaster ending!");
                return;
            }
        }
    });
    broadcastThread.start();
}

我在while（BROADCAST）行之后立即进入socket.send（packet）时，始终遇到此错误。

Exception in thread "Thread-1" java.lang.NullPointerException: null address || null buffer
at java.net.DualStackPlainDatagramSocketImpl.send(Unknown Source)
at java.net.DatagramSocket.send(Unknown Source)
at application.ContactManager$2.run(ContactManager.java:103)
at java.lang.Thread.run(Unknown Source)

我检查以确保套接字和数据包都不为空！还有什么罪魁祸首？

该错误消息的含义是什么？

编辑

我正在Windows便携式计算机上从Eclipse运行此代码。我检索IP地址并设置broadcastIP的方式是这样的：

private static InetAddress getBroadcastIp() {
    // Function to return the broadcast address, based on the IP address of the device
    try {
        String addressString = InetAddress.getLocalHost().toString();
        InetAddress broadcastAddress = InetAddress.getByName(addressString);
        return broadcastAddress;
    }
    catch(UnknownHostException e) {
        System.out.println("UnknownHostException in getBroadcastIP: " + e);
        return null;
    }

}