Java Threads错误：线程错误中的exception加上数组索引超出范围exception加上Socket Exception / Connection Exception

我正在创建两个程序文件（一个客户端一个服务器）。

每个文件都有一个线程（一个线程用于服务器，一个线程用于客户端）

在运行时，应该只有一个服务器，并且应该有多个和/或可能无限数量的客户端同时连接到服务器）

为了让多个客户端运行，用户打开多个命令提示符/ mac终端窗口（每个窗口是一个客户端）（一个窗口是服务器，因此它需要至少两个窗口才能运行）

连接客户端后，它可以向服务器发送消息（utf-8字符串）。 它还将从服务器接收从其他连接的客户端发送的所有消息（它将不接收从其自身发送的消息）。

线程/数组索引超出范围错误（eclipse）中的exception屏幕截图：

Socket Exception错误（服务器）的屏幕截图：

客户端错误的屏幕截图：

服务器代码（ChatServer.java）：

import java.io.*; import java.net.*; import java.util.*; import static java.nio.charset.StandardCharsets.*; public class ChatServer { ChatServer chatserver = new ChatServer(); private static Socket socket; public static void main(String args[]) { Thread ChatServer1 = new Thread () { public void run () { System.out.println("Server thread is now running"); try { int port_number1 = 0; int numberOfClients = 0; boolean KeepRunning = true; if(args.length>0) { port_number1 = Integer.valueOf(args[0]); } System.out.println("Waiting for connections on port " + port_number1); try { ServerSocket serverSocket = new ServerSocket(port_number1); socket = serverSocket.accept(); } catch (IOException e) { e.printStackTrace(); } System.out.println( "Listening for connections on port: " + ( port_number1 ) ); while(KeepRunning) { //create a list of clients ArrayList ListOfClients = new ArrayList(); //connect to client // socket = serverSocket.accept(); //add new client to the list, is this the right way to add a new client? or should it be in a for loop or something? ListOfClients.add("new client"); numberOfClients += 1; System.out.println("A client has connected. Waiting for message..."); ListOfClients.add("new client" + numberOfClients); //reading encoded utf-8 message from client, decoding from utf-8 format String MessageFromClientEncodedUTF8 = ""; BufferedReader BufReader1 = new BufferedReader(new InputStreamReader(socket.getInputStream(), "UTF-8")); String MessageFromClientDecodedFromUTF8 = BufReader1.readLine(); byte[] bytes = MessageFromClientEncodedUTF8.getBytes("UTF-8"); String MessageFromClientDecodedUTF8 = new String(bytes, "UTF-8"); //relaying message to every other client besides the one it was from for (int i = 0; i < ListOfClients.size(); i++) { if(ListOfClients.get(i)!="new client") { String newmessage = null; String returnMessage = newmessage; OutputStream os = socket.getOutputStream(); OutputStreamWriter osw = new OutputStreamWriter(os); BufferedWriter bw = new BufferedWriter(osw); bw.write(returnMessage + "\n"); System.out.println("Message sent to client: "+returnMessage); bw.flush(); } } } } catch (IOException e) { e.printStackTrace(); } finally { try { if (socket != null) { socket.close (); } } catch (IOException e) { e.printStackTrace(); } } } }; ChatServer1.start(); } } 

ChatClient.java代码：

 import java.io.*; import java.net.*; import java.util.*; import static java.nio.charset.StandardCharsets.*; public class ChatClient { static int numberOfClients = 0; public static void main(String args[]) { ChatClient chatclient = new ChatClient(); //If I wanted to create multiple clients, would this code go here? OR should the new thread creation be outside the while(true) loop? while (true) { String host = "localhost"; int numberOfClients = 0; Thread ChatClient1 = new Thread () { public void run() { try { //Client begins, gets port number, listens, connects, prints out messages from other clients int port = 0; int port_1number1 = 0; int numberofmessages = 0; String[] messagessentbyotherclients = null; System.out.println("Try block begins.."); System.out.println("Chat client is running"); String port_number1= args[0]; System.out.println("Port number is: " + port_number1); if(args.length>0) { port = Integer.valueOf(port_number1); } System.out.println("Listening for connections.."); System.out.println( "Listening on port: " + port_number1 ); boolean KeepRunning = true; while(KeepRunning) { for(int i = 0; i < numberOfClients; i++) { System.out.println(messagessentbyotherclients); } try { Socket clientSocket = new Socket("localhost", port); InetAddress inetlocalhost = InetAddress.getByName("localhost"); SocketAddress localhost = new InetSocketAddress(inetlocalhost, port); clientSocket.connect(localhost, port); System.out.println("Client has connected"); //client creates new message from standard input OutputStream os = clientSocket.getOutputStream(); OutputStreamWriter osw = new OutputStreamWriter(os); BufferedWriter bw = new BufferedWriter(osw); } catch (IOException e) { e.printStackTrace(); } //creating message to send from standard input String newmessage = ""; try { // input the message from standard input encoded in UTF-8 string format BufferedReader input = new BufferedReader(new InputStreamReader(System.in)); String line = ""; System.out.println( "Standard input (press enter then control D when finished): " ); while( (line= input.readLine()) != null ) { newmessage += line + " "; input=null; } } catch ( Exception e ) { System.out.println( e.getMessage() ); } //Sending the message to server String sendMessage = newmessage; try { Socket clientSocket = new Socket("localhost", port); SocketAddress localhost = null; clientSocket.connect(localhost, port); OutputStream os = clientSocket.getOutputStream(); OutputStreamWriter osw = new OutputStreamWriter(os); BufferedWriter bw = new BufferedWriter(osw); bw.write(sendMessage + "\n"); bw.flush(); } catch (IOException e) { e.printStackTrace(); } System.out.println("Message sent to server: "+sendMessage); } } finally { } } }; ChatClient1.start(); } } } 

我的问题是：我应该如何解决所有三个错误（似乎我改变了代码的一部分，然后其他错误将仍然存在或因此而被解决，但我可能是错的）？ 我还想知道是否有一种方法可以列出服务器代码中arraylist中的客户端数量，这样当客户端关闭窗口时，我可以通过从列表中删除它来保持服务器运行。