[jira] [Created] (NET-608) Exception when using addProtocolCommandListener with library org.apache.commons.net.telnet.TelnetClient

[Anthony Kearns (JIRA)]

Anthony Kearns created NET-608:
----------------------------------

             Summary: Exception when using addProtocolCommandListener with 
library org.apache.commons.net.telnet.TelnetClient
                 Key: NET-608
                 URL: https://issues.apache.org/jira/browse/NET-608
             Project: Commons Net
          Issue Type: Bug
          Components: Telnet
    Affects Versions: 3.5
         Environment: Windows 7, Java JDK 1.8, 
            Reporter: Anthony Kearns
            Priority: Minor
             Fix For: 3.6


According to the API documentation for WhoisClient and FTPClient these commands 
appear to support inherited functionality of addProtocolCommandListener.

However, when i used this as follows....i get exceptions raised for 
TelnetClient and WhoisClient but not the FTPClient.

Is this a bug or as designed? Or am I missing something ?

   import org.apache.commons.net.*;
   import org.apache.commons.net.ProtocolCommandListener;
   import org.apache.commons.net.ftp.FTPClient;
   import org.apache.commons.net.telnet.TelnetClient;
   import org.apache.commons.net.whois.WhoisClient;
   import java.io.PrintWriter;

   public class WhoisExample
   {
       public static void main(String args[])
       {
           try {
               WhoisClient whoisClient = new WhoisClient();
               whoisClient.addProtocolCommandListener(new 
PrintCommandListener(new PrintWriter(System.out)));
           }
           catch(Exception e) {
               System.out.println("whois client exception" + e);
           }

           try {
               TelnetClient telnetClient = new TelnetClient();
               telnetClient.addProtocolCommandListener(new 
PrintCommandListener(new PrintWriter(System.out)));
           }
           catch(Exception e) {
               System.out.println("telnet client exception" + e);
           }

           try {
               FTPClient ftpClient = new FTPClient();
               ftpClient.addProtocolCommandListener(new 
PrintCommandListener(new PrintWriter(System.out)));

               System.out.println("no ftp client exception here !");
           }
           catch(Exception e)
           {
               System.out.println("ftp client exception" + e);
           }
       }
   }


I get the following exception....

Caught: java.lang.NullPointerException Disconnected from the target VM, 
address: '127.0.0.1:3140', transport: 'socket' java.lang.NullPointerException 
at 
org.apache.commons.net.SocketClient.addProtocolCommandListener(SocketClient.java:772)
 at org.apache.commons.net.SocketClient$addProtocolCommandListener.call(Unknown 
Source)



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