class loading help pls!!

[gotchausa]

I'm trying to implement dynamic class loading using:
Class.forName(className, true, Thread.currentThread().getContextClassLoader());

Class A (which is a jar file residing in the /jre/lib/ext dir ) that I'm loading extends class B (which is packaged as a separate package with the main application). Next I invoke a method defined in class B, which class A should have access to (it being class B's child). So I do:

classInstance = classLoaded.newInstance();
Method M = classA.getMethod("methodNameinClassB", null);
M.invoke(classInstance, null);

When I execute my main class, I get the error about noSuchMethod. What am I doing wrong?

 

[sedj]

I expect that in this line :

Method M = classA.getMethod("methodNameinClassB", null);

your method "methodNameinClassB" does not exist - hence the error "NoSuchMethod".

 

[gotchausa]

The method exists in the class that the loaded class extends from...

 

[hologram]

Are you sure it has exactly the same signature ?

 

[gotchausa]

OK, I've been testing the problems are these:

I have 2 packages X, Y.
X contains classes 1,2,3,4,5
Y contains A.

Class 1 = main class.
It loads class A.
Class A extends from Class 2 and also imports classes 3,4.

Now I install package X under classpath /a/b/c.
I place package Y under another directory (I tried hte /jre/lib/ext to make the package an extension).

When I execute Class 1 of package X, I get an error. It complains that it cant find classes 3,4 which class A (the loaded class) uses.

I even tried putting package Y in the same dir as the main class but still get the same noClassDefFound error.