JarInputStream jis =  new  JarInputStream( new  FileInputStream(
		"c:/temp/temp.jar"));
JarEntry entry = jis.getNextJarEntry();
 while  (entry !=  null ) {
	String name = entry.getName();
	 if  (entry.getName().endsWith(".class")) {
		name = name.substring( 0 , name.length() -  6 );
		name = name.replace('/', '.');
		System.out.print(name);
		 try  {
			 Class .forName(name);
			System.out.println("\t- loaded");
		}  catch  (ClassNotFoundException e) {
			System.out.println("\t- not loaded");
		}
	}
	entry = jis.getNextJarEntry();
}

 package  com.comarch.telco.test;

 import  java.io.*;
 import  java.net.*;
 import  java.util.jar.*;

 public   class  MyJarLoader {

   public   static   void  main(String[] args)  throws  FileNotFoundException, IOException {
    String jarName = "c:/temp/temp.jar"; // заменить на свой

    URLClassLoader urlLoader = getURLClassLoader( new  URL("file",  null , jarName));

    JarInputStream jis =  new  JarInputStream( new  FileInputStream(jarName));
    JarEntry entry = jis.getNextJarEntry();
     int  loadedCount =  0 , totalCount =  0 ;

     while  (entry !=  null ) {
      String name = entry.getName();
       if  (name.endsWith(".class")) {
        totalCount++;
        name = name.substring( 0 , name.length() -  6 );
        name = name.replace('/', '.');
        System.out.print("> " + name);

         try  {
          urlLoader.loadClass(name);
          System.out.println("\t- loaded");
          loadedCount++;
        }  catch  (Throwable e) {
          System.out.println("\t- not loaded");
          System.out.println("\t " + e.getClass().getName() + ": " + e.getMessage());
        }

      }
      entry = jis.getNextJarEntry();
    }

    System.out.println("\n---------------------");
    System.out.println("Summary:"); 
    System.out.println("\tLoaded:\t" + loadedCount); 
    System.out.println("\tFailed:\t" + (totalCount - loadedCount)); 
    System.out.println("\tTotal:\t" + totalCount); 
  }
  
   private   static  URLClassLoader getURLClassLoader(URL jarURL) {
     return   new  URLClassLoader( new  URL[]{jarURL});
  }
}