title: Android Async tasks reuse
body: <p>I am developing an app where in a number of the activities I need to retrieve data via Http.
  Once I have the data I process it in the onPostExecute() callback method.</p>
  
  <p>This works fine if I define the async task as an inline class, but as I want to do the same processing in a number of activities I have defined it as an external class.</p>
  
  <p>So the question is, using an external class how do I signal an "event" back to the calling class as a means of passing the data back. I know how to do this in C# but I am new to Java and can not see how to achieve this.</p>