java - 字符串 "For input string: "-l"被执行并输出，即使它不存在于代码中(java线程)

Question

该程序的目的是从服务器向客户端发送文本消息(UTF-8 字符串)，反之亦然，就像两个人在手机上互相发短信一样(一部手机是客户端，一部手机是服务器) )

在下面的屏幕截图中，有一个输出显示“对于输入字符串:“-l”，但代码中实际上并不存在。

一共有三个文件，一个是主要功能，一个是服务端，一个是客户端。

命令行参数“-l”(如果存在)将运行服务器线程/服务器文件。

如果“-l”不存在，它将运行客户端线程/客户端文件。

DirectMessengerCombined.java代码(主函数文件):

public class DirectMessengerCombined
{

    public static void main(String[] args)
    {
        DirectMessengerClient Client1 = new DirectMessengerClient();
        DirectMessengerServer Server1 = new DirectMessengerServer();
          for (int i = 0; i < args.length; i++)
          {
                boolean Client = false;
                boolean Server = false;
                if(args[0].equals("3000"))
                {
                    Client1.ClientRun(args);
                }
            switch (args[0].charAt(0))
              {
                case '-':
                 if(args[0].equals("-l"))
                 {  
                     Server = true;
                     if(Server==true)
                     {
                         Server1.ServerRun(args);
                     }
                 }

              }
            i=args.length + 20;



          } 
    }

}

DirectMessengerServer.java代码:

import java.io.*;
import java.net.*;
import java.util.*;
//import static java.nio.charset.StandardCharsets.*;
public class DirectMessengerServer
{
    void ServerRun(String[] args)
    {

        Thread Server = new Thread () 
        {
              public void run ()
              {   
                    //String address="127.0.0.1";
                    System.out.println("Server thread is now running");
                    try
                    {
                         System.out.println("Try block begins..");
                         int port_number1= Integer.valueOf(args[0]);
                        System.out.println("Port number is: " + port_number1);
                        // listener = new ServerSocket(port_number1);
                      //   SocketAddress addr = new InetSocketAddress(address, port_number1);
                         System.out.println("Listening for connections..");
                         System.out.println( "Listening on port: " + ( port_number1 ) );
                      //   client_socket= server_socket.accept();
                     //    BufferedReader reader= new BufferedReader(new InputStreamReader(client_socket.getInputStream(), "UTF8"));
                      //   PrintWriter output= new PrintWriter( client_socket.getOutputStream(), true );
                      //   outputstream = new DataOutputStream(smtpSocket.getOutputStream());
                      //   inputstream = new DataInputStream(smtpSocket.getInputStream());
                      //   String input_line= reader.readLine();
                         System.out.println( "Received from client: " );
                       //  System.out.println( input_line );
                      //   output.println( input_line );
                            }
                            catch ( Exception e )
                            {
                                System.out.println( e.getMessage() );
                            }  
                        }
        };
        Server.start();
    }
}

DirectMessengerClient.java代码:

import java.io.*;
import java.net.*;
import java.util.*;
import static java.nio.charset.StandardCharsets.*;
public class DirectMessengerClient
{
    //static String[] arguments;
    //public static void main(String[] args)
    //{
    //  arguments = args;
    //}
    public DirectMessengerClient()
    {

        //System.out.println("test.");

    }
    public void ClientRun(String[] args)
    {
        Thread Client = new Thread ()
        {
          public void run()
          {   
                System.out.println("Client thread is now running");
              //  String address="127.0.0.1";
              //  ServerSocket server_socket = null;
              //  Socket client_socket = null;
                //Socket smtpSocket = null;  
                DataOutputStream outputstream;
                DataInputStream inputstream;
                try
                {
                            System.out.println("Try block begins..");
                            int port_number1= Integer.valueOf(args[0]);
                            System.out.println("Port number is: " + port_number1);
                           // listener = new ServerSocket(port_number1);
                         //   SocketAddress addr = new InetSocketAddress(address, port_number1);
                            System.out.println("Listening for connections..");
                            System.out.println( "Listening on port: " + Integer.toString( port_number1 ) );
                         //   client_socket= server_socket.accept();
                        //    BufferedReader reader= new BufferedReader(new InputStreamReader(client_socket.getInputStream(), "UTF8"));
                         //   PrintWriter output= new PrintWriter( client_socket.getOutputStream(), true );
                         //   outputstream = new DataOutputStream(smtpSocket.getOutputStream());
                         //   inputstream = new DataInputStream(smtpSocket.getInputStream());
                         //   String input_line= reader.readLine();
                            System.out.println( "Received from client: " );
                          //  System.out.println( input_line );
                         //   output.println( input_line );
                }
                catch ( Exception e )
                {
                            System.out.println( e.getMessage() );
                }

          }
        };

    Client.start(); 
    }
}

我的问题是:当代码中实际不存在“for input string "-l”时，如何输出它？

Answer 1

它正在由您的 System.out.println( e.getMessage() ); 打印。

您不应该这样做，因为您会发现它很令人困惑并且它没有描述整个异常。请改用e.printStackTrace();。

在您成功看到完整的异常后，通过更改来修复您的代码

int port_number1= Integer.valueOf(args[0]);

至

int port_number1= Integer.valueOf(args[1]);