Comparing element values in ViewPager

Comparing element values in ViewPager

What is needed: Preforming comparisons between items.
The problem: Working inside the ViewPager I don't exactly know how to
implement checks between two buttons disguised as a spinner triggering a
datePicker. What I am trying now is calling a method on
onActivityCreated(Bundle savedInstanceState). This method calls on both
their values and checks to see if they are null, if the are not null the
method compares their value. The current implementation on works when the
Pager is loaded. For value changes the method is implemented on Listener
events(though the method is never called).
Can someone please guide me through the implementation