title: Global Set of variables for android app and modify them in different activities
body: <p>I am sure this has already been answered but going through alot of the other Questions/Answers it isn't that clear to me. So I will explain what I am trying to do.</p>
  
  <p>I am making a tycoon type android game that starts from a Menu Screen that goes to the Playscreen and there you have a status bar on top with Cash and Supply info, and  buttons to go to a SupplyBuyScreen, UpgradeScreen, etc... I am trying to update the status bar values as things are purchased and those values have to transfer between each different activity and some will get modified and come back to the PlayScreen. </p>
  
  <p>I was thinking of using SharedPreferences and am having trouble setting it up. Any pointers??</p>