title: How to launch android applications from another application
body: <p>I want to launch any one of the existing android applications (contacts, call dialer, etc.)
  from my app upon on click of a button.</p>
  
  <p>All that I know is to get the Intent of the particular app and start the activity. But I don't  know how to set the class path for the intent for contacts.</p>
  
  <p>Am I following the correct solution? What is the way to launch another application?</p>