java - 向所有客户端发送消息时出现 ConcurrentModificationException

Question

我在迭代套接字的 ArrayList 时遇到问题。该列表的目的是当除最后一个客户端之外的另一个客户端连接时向所有客户端发送消息。我收到 ConcurrentModificationException 并且我不知道如何管理它。请帮忙!

服务器程序:

 public void start() {

    try {
        serverSocket = new ServerSocket(10001);
        thread = new Thread(new MessageClient(listOfClients));
        thread.start();
        while (!isStopped) {
        socket = serverSocket.accept();
        listOfClients.add(socket);
        synchronized (listOfClients) {
            listOfClients.notifyAll();
        }
        g.getTextArea().append(
            "Client number " + listOfClients.size()
                + " has connected.\n");
        threadClient = new Thread(new SerThread(socket, listOfClients));
        threadClient.start();
        }
    } catch (IOException e) {
    }
    }

线程程序(MessageClient):

public void run() {
    while (true) {
        for (Iterator<Socket> cl = listOfClients.iterator(); cl.hasNext();) {
        synchronized (listOfClients) {
            cur = cl.next();
            if (!cur.equals(listOfClients.get(listOfClients.size() - 1))) {
            try {
                System.out.println("dddddddd");
                ous = new PrintWriter(cur.getOutputStream());
                ous.println("Client " + listOfClients.size()
                    + " has connected.");
                ous.flush();
            } catch (IOException e) {
                JOptionPane
                    .showMessageDialog(null,
                        "There was a problem getting your outputstream.");
            }
            try {
                System.out.println("ddd");
                listOfClients.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            }
        }
        }
    }
    }

Answer 1

这个问题的解决方案就是使用synchronizedList。它会自动处理线程之间的同步。