title: Checking for existing instance of activity before launching
body: <p>I wish to launch an activity (GameActivity) from my homescreen activity, but I'd like to check that there isn't already an instance of it before doing so.  If there is already an instance, I'd like to call finish() on it, and then proceed with starting my new GameActivity.</p>
  
  <p>This - <a href="https://stackoverflow.com/questions/1624338/android-return-to-previous-activity-without-calling-finish">Android: Return to previous activity without calling finish()</a> - suggested creating a static method in the Activity to kill any existing instances, but I'm not sure what this method would look like (crucially - how does it find and act upon the existing instance of the Activity?).</p>
  
  <p>Thanks a lot - hope someone can help!</p>