I have problem when use Jakarta Commons Net in Java

[wintersun]

Hi you, I'm new in Network Programming in Java and I'm excuting a FTP class to list all files and directories information from FTP Host . But I had a problem when I try to use "org.apache.commons.net.ftp" package in Jakarta Commons Net Library. It logins OK but fail when try list information in current working directory .
Error:
220 ftp1.0catch.com NcFTPd Server (licensed copy) ready.
Workdir >>/
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/oro/text/regex/MalformedPatternException
at org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory.createUnixFTPEntryParse r(DefaultFTPFileEntryParserFactory.java:169)
at org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory.createFileEntryParser(D efaultFTPFileEntryParserFactory.java:94)
at org.apache.commons.net.ftp.FTPClient.initiateListParsing(FTPClient.java:2358)
at org.apache.commons.net.ftp.FTPClient.listFiles(FTPClient.java:2141)
at org.apache.commons.net.ftp.FTPClient.listFiles(FTPClient.java:2188)
at JClient.FTPClientTrial.useFTP(FTPClientTrial.java:52)
at JClient.FTPClientTrial.main(FTPClientTrial.java:23)
Java Result: 1

CODE :
import java.text.DateFormat;
import java.util.Date;
import org.apache.commons.net.ftp.*;

import java.io.*;
public class FTPClientTrial {
public static void main(String[] args) {
new FTPClientTrial().useFTP("ftp://thanhnam-it.0catch.com", "/", "J://AcrobatReader//Readme.htm",
"usernam", "password");
}

public void useFTP(String ftpserver, String directoryName,
String filetoUpload, String username, String password) {
FTPClient ftpClient = new FTPClient();

try {
ftpClient.connect(ftpserver);
System.out.print(ftpClient.getReplyString());

// check reply code.
if (!FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
ftpClient.disconnect();
System.out.println("Connection refused.");
return;
}

ftpClient.login(username, password);
System.out.println("Workdir >>" +
ftpClient.printWorkingDirectory());

//Store file
FileInputStream input = new FileInputStream(filetoUpload);
ftpClient.storeFile(filetoUpload, input);

//ERROR HERE : List all Files and directories
FTPFile[] files = ftpClient.listFiles(); System.out.println( "Number of files in dir: " + files.length );
DateFormat df = DateFormat.getDateInstance( DateFormat.SHORT );
for( int i=0; i<files.length; i++ )
{
Date fileDate = files[ i ].getTimestamp().getTime();

// Download a file from the FTP Server
System.out.print( df.format( files[ i ].getTimestamp().getTime() ) );
System.out.println( "\t" + files[ i ].getName() );
File file = new File( "/directory" + File.separator + files[ i ].getName() );
FileOutputStream fos = new FileOutputStream( file );
ftpClient.retrieveFile( files[ i ].getName(), fos );
fos.close();
file.setLastModified( fileDate.getTime() );
}

ftpClient.logout();
ftpClient.disconnect();
System.out.println("Disconnected");

} catch (IOException e) {
if (ftpClient.isConnected()) {
try {
ftpClient.disconnect();
System.out.println("Disconnected");
}
catch (IOException f) {
// do nothing
}
}

e.printStackTrace();
}
finally {
try {
ftpClient.logout();
ftpClient.disconnect();
}
catch (IOException f) {
System.out.println("Disconnected");
}
}
}
}
---------------------
So I don't understand what type of error and how I can solve it? Anyone show me? Thank u a lot!