java reflection call methods of an already loaded object

Question

How can I call the method of an object that has already been loaded in the JVM using reflection? I tried

Class myClass = Class.forName("myClass");
Method m = com.test.class.getDeclaredMethod("getValue",new Class[] {});
Object result = m.invoke(myClass,null);

but i get java.lang.IllegalArgumentException: object is not an instance of declaring class. The method I want to call is void i.e. does not take parameters

UPDATE I have an application that has already loaded a class "A". Another class "B" will be instantiated by a framework. When class "B" is initialized, class "A" has already been loaded in the JVM. I want to call a method from loaded instance of class "A" BUT without having a reference to "A" in class "B". In the answers, it seems I must create a new instance of "A" in class "B" but I want access to an already loaded object. If I create a new instance of "A" in "B" why would I want to use reflection? Am I missunderstanding something?

Thanks

Answer 1

You're passing the instance of Class as the first parameter to Method.invoke(..), but that's wrong; you want to pass the instance you're interested in.

result = m.invoke(myInstance, null);