java - 如何从 ArrayList 中摆脱 IndexOutOfBoundsException

Question

当我启动服务器并且客户端连接到它时，我收到此错误:

Waiting for clients ...
Client connected from: Driton PC
java.lang.IndexOutOfBoundsException: Index: 1, Size: 1

我不太明白为什么会发生这种情况，当我从互联网上跟随另一个人并且他的示例有效而我的示例无效时

public class ChatServer { 

public static ArrayList<Socket> ConnectionArray = new ArrayList<Socket>();

public static ArrayList<String> CurrentUsers = new ArrayList<String>();

public static void main(String[] args) throws IOException{
    try
    {
        final int PORT = 444;
        ServerSocket SERVER = new ServerSocket(PORT);
        System.out.println("Waiting for clients...");

        while(true)
        {
            Socket SOCK = SERVER.accept();
            ConnectionArray.add(SOCK);
            System.out.println("Client connected from: "+ SOCK.getLocalAddress().getHostName());
            AddUserName(SOCK);
            Chat_Server_Return CHAT = new Chat_Server_Return(SOCK);
            Thread x = new Thread(CHAT); 
            x.start();
        }
    }
        catch(Exception x){System.out.println(x);}
}

public static void AddUserName(Socket X) throws IOException
{
    Scanner INPUT = new Scanner(X.getInputStream());
    String UserName = INPUT.nextLine();
    CurrentUsers.add(UserName);
    for(int i = 1; 1 <= ChatServer.ConnectionArray.size(); i++){
        Socket TEMP_SOCK = (Socket) ChatServer.ConnectionArray.get(i-1);
        PrintWriter OUT = new PrintWriter(TEMP_SOCK.getOutputStream());
        OUT.println("#?!"+ CurrentUsers);
        OUT.flush();

    }
}

它运行 for 循环两次。

Answer 1

如果没有删除任何内容，则 for 循环的条件不正确。更改为:

i <= ChatServer.ConnectionArray.size()

但是处理 for 循环的传统方法是遵循从 0 开始的索引，并且而不是稍后减一:

for(int i = 0; i < ChatServer.ConnectionArray.size(); i++){
    Socket TEMP_SOCK = (Socket) ChatServer.ConnectionArray.get(i);