title: Android Lock Apps
body: <p>I'm new here and I've searched for questions to help me but I have no clear answers.</p>
  
  <p>I need to make an application to block other applications on the phone.
  I've seen several on the market but I want to make one.
  is there any way of knowing when a user tries to open an application and bring forward an activity? (to put the password). </p>
  
  <p>I tried with FileObserver, but only works with files and directories (obviously).
  Could I make a listener that captures the Intent of the other applications before starting?</p>
  
  <p>I apologize for my english and I appreciate your help!</p>