title: How can I update information in an Android Activity from a background Service
body: <p>I am trying to create a simple Android application that has a ActivityList of information, when the application starts, I plan to start a Service that will be constantly calculating the data (it will be changing) and I want the ActivityList to be in sync with the data that the service is calculating for the life of the app.</p>
  
  <p>How can I set up my Activity to be listening to the Service? Is this the best way to approach this problem?</p>
  
  <p>For example, if you imagine a list of stock prices - the data would be being changed regularly and need to be in sync with the (in my case) Service that is calculating/fetching the data constantly.</p>
  
  <p>Thanks in advance</p>