Accessing the lowest exception message

[tm_sss]

Hi all,

I'm relatively new to Java (4 hrs in) and I've managed to get an SFTP implementation working. However, in trying to break it, I realised that the component (Zehon) that I'm using, raises exceptions with messages that aren't as descriptive as the library it is calling Jsch.

04/11/2009 2:12:51 PM org.apache.commons.vfs.VfsLog info
INFO: Using "C:\DOCUME~1\trentm\LOCALS~1\Temp\vfs_cache" as temporary files store.
org.apache.commons.vfs.FileSystemException: Could not connect to SFTP server at "sftp://temp:***@sftpserver/".
com.zehon.exception.FileTransferException: org.apache.commons.vfs.FileSystemException: Could not connect to SFTP server at "sftp://temp:***@sftpserver/".
  at com.zehon.FileTransferClient.resourceExist(FileTransferClient.java:576)
  at com.zehon.FileTransferClient.folderExists(FileTransferClient.java:551)
  at com.zehon.sftp.SFTPClient.folderExists(SFTPClient.java:803)
  at SFTP.IdfJSFTP.jSFTPPut(IdfJSFTP.java:69)
  at SFTP.IdfJSFTP.main(IdfJSFTP.java:26)
Caused by: org.apache.commons.vfs.FileSystemException: Could not connect to SFTP server at "sftp://temp:***@sftpserver/".
  at org.apache.commons.vfs.provider.sftp.SftpFileProvider.doCreateFileSystem(SftpFileProvider.java:99)
  at org.apache.commons.vfs.provider.AbstractOriginatingFileProvider.getFileSystem(AbstractOriginatingFileProvider.java:103)
  at org.apache.commons.vfs.provider.AbstractOriginatingFileProvider.findFile(AbstractOriginatingFileProvider.java:82)
  at org.apache.commons.vfs.provider.AbstractOriginatingFileProvider.findFile(AbstractOriginatingFileProvider.java:66)
  at org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:692)
  at org.apache.commons.vfs.impl.DefaultFileSystemManager.resolveFile(DefaultFileSystemManager.java:620)
  at com.zehon.FileTransferClient.getFileObject(FileTransferClient.java:741)
  at com.zehon.FileTransferClient.resourceExist(FileTransferClient.java:573)
  ... 4 more
Caused by: org.apache.commons.vfs.FileSystemException: Could not connect to SFTP server at "sftpserver".
  at org.apache.commons.vfs.provider.sftp.SftpClientFactory.createConnection(SftpClientFactory.java:214)
  at org.apache.commons.vfs.provider.sftp.SftpFileProvider.doCreateFileSystem(SftpFileProvider.java:90)
  ... 11 more
Caused by: com.jcraft.jsch.JSchException: Auth fail
  at com.jcraft.jsch.Session.connect(Session.java:452)
Unknown Exception
  at com.jcraft.jsch.Session.connect(Session.java:150)
  at org.apache.commons.vfs.provider.sftp.SftpClientFactory.createConnection(SftpClientFactory.java:210)
  ... 12 more

The message I want to return is actually the line:
Caused by: com.jcraft.jsch.JSchException: Auth fail

How do I access that?

Regards,
TM

[RamyaSivakanth]

just if u want to print only the exact messages.

say

try
{
ur code will be here
}
catch(Exception ex)
{
System.out.println(ex);//it prints the eception caused by in single line

}//try-catch

[masijade]

getCause recursively until you get the one you want?

[rsvedula]

I am trying to use zehon but get a error

"at org.apache.commons.vfs.impl.DefaultFileSystemManag er.setupComponent(DefaultFileSystemManager.java:42 9)
at org.apache.commons.vfs.impl.DefaultFileSystemManag er.setReplicator(DefaultFileSystemManager.java:388 )
at org.apache.commons.vfs.impl.StandardFileSystemMana ger.init(StandardFileSystemManager.java:100)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.apache.commons.vfs.VFS.createManager(VFS.java: 89)
at org.apache.commons.vfs.VFS.getManager(VFS.java:51)
at com.zehon.FileTransferClient.getFileObject(FileTra nsferClient.java:729)
at com.zehon.FileTransferClient.resourceExist(FileTra nsferClient.java:573)"

I am not able to figure out the issue?

Any inputs please?

[r035198x]

Did you read Masi's response? What code did you write to implement that suggestion?

[tm_sss]

masijade,

Thanks for the tip. Worked the charm.

For anyone looking for the same type of thing. To implement I assigned the getCause() of the exception to a Throwable type variable, then evaluated the results.

Throwable chain = e.getCause();
    
while (chain != null) {
  chain = chain.getCause();

  if (chain == null) break;
  lastMessage = chain.getMessage();
  
}

Regards,
TM

[r035198x]

Make it generic and write a method called getCauseOfType that takes two parameters. The one is the Exception and the other is the type of exception one is looking for. Put that in an Exceptions class and file it under your utility functions project.

[Tolls]

This is one of those instances where recursion might be a neater solution, but that's just me being awkward...:)

[r035198x]

This is one of those instances where recursion might be a neater solution, but that's just me being awkward...:)

Mine is recursively implemented too ...

[Tolls]

Great minds, etc etc...