message += "port: " + PORT_NUMBER + "\n"; // port number
message += "device_address_long: " + DEVIDE_MAC_ADDRESS + "\n";
DatagramPacket sendPacket = new DatagramPacket(message.getBytes(), message.getBytes().length, InetAddress.getByName("192.168.2.227"), 5005); // address and port of the gateway which means Raspberry PI's IP address
message += "port: " + PORT_NUMBER + "\n"; // port number
message += "device_address_long: " + DEVIDE_MAC_ADDRESS + "\n";
DatagramPacket sendPacket = new DatagramPacket(message.getBytes(), message.getBytes().length, InetAddress.getByName("192.168.2.227"), 5005); // address and port of the gateway which means Raspberry PI's IP address