title: OnPause(), OnResume() and OnDestroy
body: <p>I have developed a small app which uses several different classes to allow the user to add,remove and view certain data. I use an arrayList to store entries and this has its own class which has methods linked to the array so i can access the array from all of my classes.</p>
  
  <p>I want to introduce the above methods to optimise my code and was wondering if I could stick them in one class hopefully the same application class I have my array in and there just define them where they will be getting used, this will save me having to write the same piece of code in several classes, is this possible?</p>
  
  <p>Thanks</p>