First of all let me say I am aware of type erasure.

Let's say I have something like:

ArrayList<Integer> foo=new ArrayList<Integer>();

is there any way at run time to determine the type parameter is
Integer... more specifically if
I have

public interface MyClass<T>
{
...
}

public class MyClassImpl<T> implements MyClass<T>
{
...
}

public class MockMyClass<T> implements MyClass<T>
{
...
}

public
Is there any way of knowing the value of T at run time.

If the above is not possible maybe there is still a way to accomplish
what I have in mind.... basically if some class does the following:

public class MyApp<T>
{
      private ArrayList<T> data;

      public MyApp()
       {
             data=new ArrayList<T>();
       }
....
}

I want to be able to replace T with TImpl (i.e. in the case of MyClass
replace it with an instance of MockMyClass [NOT MyClassImpl]) {this
needs to be done via reflection and not modifing the source code}....
Note I already have something that works for single instances and
arrays but not for collections (thus the need for determing the generic
type)