static void Main(string[] args) { ChatRoom chatroom = new ChatRoom(); User user1 = new User(chatroom, "1", "Alex"); User user2 = new User(chatroom, "2", "Brian"); User user3 = new User(chatroom, "3", "Charles"); User user4 = new User(chatroom, "4", "David"); chatroom.addUser(user1); chatroom.addUser(user2); chatroom.addUser(user3); chatroom.addUser(user4); user1.send("Hello brian", "2"); user2.send("Hey buddy", "1"); }