Add JARs to classpath within Java

Question

I've read through a number of different posts on this topic, but can't seem to get my code working.
I want to write a class that will run embedded Tomcat. For certain reasons, I can't set the
classpath to Tomcat before my class gets called, so I want to locate the Tomcat JARs, add them
using a ClassLoader and then call the appropriate classes to setup and run Tomcat. An
exception is being thrown, so I'm doing something wrong. Any ideas?
Here's the code I'm trying to add the JARs with:
String mcatHome = "tomcat/lib"
try {
     // Scan folder for JARs and build URL array
     File mcatDir = new File(mcatHome);
     File files[] = mcatDir.listFiles(new JarFilter());
     URL jarURLs[] = new URL[files.length];
     for (int i = 0; i < files.length; i++)
          jarURLs[i] = files.toURL();
     // Add list of JARs to class loader
     URLClassLoader ucl = new URLClassLoader(jarURLs);
     // Use loader when loading classes
     Thread.currentThread().setContextClassLoader(ucl);
catch (Exception ex) {
then I call the contructor on the class which tries to start Tomcat:
     public void Mcat()
          startTomcat();
     protected void startTomcat()
          Embedded embed = new Embedded();
When the constructor is invoked, I get:
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/catalina/L
ifecycleException

Answer 1

jschell, the list of JARs is generated from listing them in the folder. I did print the list out and
the URLs looked ok. (i.e. file:/....)
Here a snippet of how the class calling is setup:
In Runner.java:
public void Runner()
     //code from original post to load JARs
     Mcat mcat = new Mcat()
In Mcat.java:
import org.apache.catalina.*;
import org.apache.catalina.logger.*;
import org.apache.catalina.users.*;
import org.apache.catalina.realm.*;
import org.apache.catalina.startup.Embedded;
public class Mcat
    public void Mcat()
        startTomcat();
    protected void startTomcat()
        Embedded embed = new Embedded();
}Hope this helps