无法访问类型为...的封闭实例 [英] No enclosing instance of type ... is accessible

问题描述

出于教育目的，我试图制作一个服务器和一个客户端，其中服务器从多个客户端接收数据并回显每条消息.问题是，当我尝试让服务器一次将回显发送到所有客户端时.

For educational purposes I tried to make a server and client where the server receives data from multiple clients and echoes each message. The problem is when I try to make the server send the echo to all of the clients at once.

public class SocketServer {
  ArrayList<MyRunnable> ts = new ArrayList<MyRunnable>();
  ServerSocket serv;
  static MainServerThread mst = new MainServerThread();
//                                  ^ IDE(eclipse) underlines this as the problem
  SocketServer() {
    EventQueue.invokeLater(mst);
  }

  public static void main(String[] args) { 
    Thread tr = new Thread(mst);
    tr.start();
  }

  void send(String s) {
    for (int i = 0; i < ts.size(); i++) {
      MyRunnable tmp = ts.get(i);
      tmp.sendToClient(s);
    }
  }

  class MainServerThread implements Runnable {
    public void run() {
      try {
        serv = new ServerSocket(13131);
        boolean done = false;
        while (!done) {
          Socket s = serv.accept();
          MyRunnable r = new MyRunnable(s);
          Thread t = new Thread(r);
          ts.add(r);
          t.start();
        }
      } catch(Exception e) {
        e.printStackTrace();
      }
    }
  }

  class MyRunnable implements Runnable {
    Socket sock;
    PrintWriter out;
    Scanner in;
    MyRunnable(Socket soc) {
      sock = soc;
    }

    public void run() {
      try {
        try {
          out = new PrintWriter(sock.getOutputStream(), true);
          in = new Scanner(sock.getInputStream());
          boolean done = false;
          while (!done) {
            String line = in.nextLine();
            send("Echo: " + line);
            System.out.println("Echo: " + line);
            if (line.trim().equals("BYE")) done = true;
          }
        } finally {
          sock.close();
        }
      } catch (Exception e) {
        e.printStackTrace();
      }
    }

    public void sendToClient(String s) {
      out.println(s);
    }
  }
}    

我已经搜索并回答了许多类似的问题，但是没有一个对我有帮助.希望你能指出我的错误.预先感谢.

I have searched for and answer and saw many similar questions, but none of them helped me. Hope you can point out my mistake. Thanks in advance.

推荐答案

您的嵌套类需要外部类的实例，因为它不是静态的-但是您没有拥有的实例外层阶级.

Your nested class requires an instance of the outer class, because it's not static - but you don't have an instance of the outer class.

尝试使两个嵌套类都变为 static .看起来他们 都不是对外部类的引用.

Try making both of your nested classes static. It doesn't look like they need a reference to the outer class anyway.

事实上，我很想避免为此使用嵌套类-尽管嵌套类有时确实有用，但它们有各种极端情况，通常创建单独的顶层类型更干净.

In fact, I'd be tempted to avoid using nested classes at all for this - while nested classes can certainly be useful sometimes, they have various corner cases, and it's typically cleaner to create separate top-level types.

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