title: How can two programs talk to each other in Java?
body: <p>I want to ‪reduce‬ the CPU usage/ROM usage/RAM usage - generally‬, all system resources that my app uses - who doesn't? :)</p>
  
  <p>For this reason I want to split the preferences window from the rest of the application,
  and let the preferences window to run as ‪independent‬ program.</p>
  
  <p>The preferences program ‪should‬ write to a <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Properties.html" rel="nofollow noreferrer">Property</a> file(not a problem at all) and to send a "update signal" to the main program - which means it should call the update method (that i wrote) that found in the Main class.</p>
  
  <p>How can I call the update method in the Main program from the preferences program?</p>
  
  <p>To put it another way, is a way to build preferences window that take system resources <b>just</b> when the window appears?</p>
  
  <p>Is this approach - of separating programs and let them talk to each other (somehow) - the right approach for speeding up my programs?</p>