Overwriting a declared method?

Hello, I'm messing with something Java based, I want to modify it a bit. My code is simply this:

Method xyzMethod = XYZ.class.getDeclaredMethod("a", int.class, int.class, int.class, int.class, Random.class);

Method xyzMethod = XYZ.class.getDeclaredMethod("a", int.class, int.class, int.class, int.class, Random.class);

Now the issue is that unlike the Field class, Method doesn't seem to have a

set

set

method. So, if I wanted to override this function - how?