Add jar files and use those classes at the runtime

Question

Hi All,
I need to add some jar files at the runtime depends on which the user selects where the jar file is located and i need to import those classes in other class for some functionalities . I could add jar files by using the URLClassLoader and Class.forName("myjar.myclassname") is also succeeded and i have no clue how to use those classes with in the jar file as i couldn't import those classes also in the source because the jar files are being added at the runtime(This leads to class not found exception at the compile time).
I had found a complicated way of using those classes after being added at the run time as below.
   Class clazz = Class.forName(myClass);
            final Method method = clazz.getDeclaredMethod(requiredMethod, new Class[]{URL.class});
            final Object returned = method.invoke(clazz.newInstance(), new Object[]{request}); but, its really pain to use in this way in all the places.
Does any of you have simpler suggestions on how to achieve this?
Thanks,
Venky.

Answer 1

Thanks jschell. Yes, you are right. I had found that using reflection API is the only way to load classes at the run time. But according to our application using reflection makes the application little complex, so while start of the application or during other modifications, i am overwriting my jar file to the latest one using FileChannel class as below
      FileChannel ic = new FileInputStream("new.jar").getChannel();
      FileChannel oc = new FileOutputStream("old.jar").getChannel();
      ic.transferTo(0, ic.size(), oc);
      ic.close();
      oc.close();After this code is executed, our application totally uses the new jar file.It is little fast than using reflection. Is this a good idea?