System poerties class path is not working

Question

I am using reflection to call my class's main method.
For that i am loading a class by Class.forName method and then calling main method.
if i am using set classpath="path to be used" command on command prompt then it finds the class, loads it and calls the main method.
but
if i am setting the class path by System class
i.e. System.setProperty("java.class.path", "path to be used") then it is not able to find the class and gives me exception "java.lang.ClassNotFoundException".
i have also cross checked whether the class path is set properly by calling method System.getProperty("java.class.path"); it returns me the same class path which i had set by calling
System.setProperty("java.class.path", "path to be used")
Can you please some one help me to solve this problem where i am missing any step or we can't do this way?
or you can tell me the alternate way by which i can set the class path dyanamically.

Answer 1

i want to call the class main method, for that i am sending runtime the class name, and classpath of jar files,
Problem is with the class path.This work by setting classpath by command promopt's command set classpath. But then every time i have to change the classpath by using set classpath command. i dont want this approch so i am trying to do with System.setProperties("java.class.path","path to be used") but not worked give me exception class not found. please refer the following code.
                                                    System.setProperty("java.class.path", classpath);
               Class product= Class.forName("className");
               Class classArray[] = {String.class};
               Object argsArray[] = {"parameterst to method"};
               Method mainMethod = product.getMethod("main", classArray);
               mainMethod.invoke(null, argsArray);With this code it gives me exception class not found.