如何将数组列表的元素从另一个类复制到另一个类

Question

我的程序在执行过程中遇到错误，因为NewServer中的arrlist元素未复制到MyConnection。 我该怎么办？

MyConnection负责发送和获取消息以及将消息分发给所有客户端。

public class MyConnection extends Thread{
    Socket s;
    BufferedReader in;
    PrintWriter out;
    String reps, msg;
    ArrayList<MyConnection> arrlist;


    MyConnection(Socket s, ArrayList<MyConnection> arrlist){
        this.arrlist = arrlist;
        this.s = s; 

        try{
            this.in= new BufferedReader(new InputStreamReader(s.getInputStream()));
            this.out= new PrintWriter(new OutputStreamWriter(s.getOutputStream()));
        }catch(IOException e){
            System.out.println("Something Bad Happened " + e);
        }
    }


    boolean sendMessage(String msg){

        try{
            NewServer server = new NewServer();
            server.sendtoAll(msg);
            out.println(msg);
            out.flush();   
             System.out.println(server.arrlist.size());
            return true;


        }catch (Exception e) {
            System.out.println("S: Something bad happened :(");
            e.printStackTrace();
            return false;
        }
    }
    String getMessage(){
        try{          

            reps = in.readLine();


        }catch (Exception e) {
            System.out.println("S: Something bad happened :(");
            e.printStackTrace();
        }


            return reps;
     } 
}

这是NewServer

public class NewServer{
static ArrayList<MyConnection> arrlist = new ArrayList<MyConnection>();
static boolean push;
static Socket s;

public void sendtoAll(String message){

    for(int i= arrlist.size(); i >= 0; i--){
        MyConnection t3 = arrlist.get(i);
        t3.sendMessage(message);
        if(!t3.sendMessage(message)){
            arrlist.remove(i);
            System.out.println("Client disconnected");
        }
    }

}
public static void main(String args[]){
    try{
        System.out.println("S: Starting server...");
        ServerSocket ssocket = new ServerSocket(8888);
        System.out.println("S: Waiting for connections...");

        while(true){

            s = ssocket.accept();
            System.out.println("SOMEONE CONNECTEDDDDD" + arrlist.size());
            MyConnection t = new MyConnection(s,arrlist);
            arrlist.add(t); //put my connection to arrlist
            t.start();

        }

    }catch(Exception e) {
        System.out.println("Soooomething Bad Happened " + e);
    }
}

Answer 1

您将无法编辑要迭代的列表，可以执行以下操作：

public void sendtoAll(String message){
    ArrayList<MyConnection> tempArrlist = new ArrayList<MyConnection>()
    for(int i= arrlist.size(); i >= 0; i--){
        MyConnection t3 = arrlist.get(i);
        t3.sendMessage(message);
        if(t3.sendMessage(message)){
            tempArrlist.add(arrlist.get(i));
        } else {
             System.out.println("Client disconnected");
        }
    }
    arrlist = tempArrlist;
}