chatroomService property Null safety
final
聊天室服务,提供加入、退出、发送和接收聊天室消息等功能;
Implementation
final ChatroomService chatroomService = ChatroomService();
聊天室服务,提供加入、退出、发送和接收聊天室消息等功能;
final ChatroomService chatroomService = ChatroomService();