android - Launching installedapplication -

how launch installed application?

i have installed using below: file file = new file(dir, "app.apk");

intent intent = new intent(intent.action_view);  intent.setdataandtype(uri.fromfile(file), "application/vnd.android.package-archive");  startactivity(intent); 

second time, checking if package installed, if yes, want launch.

intent intent = new intent(com.example.app);

thanks in advanced!

i'm using method. should change package , class names.

     private static final string gps_status_package_name = "com.eclipsim.gpsstatus2";     private static final string gps_status_class_name = "com.eclipsim.gpsstatus2.gpsstatus";    /**      * run gpsstatus & toolbox application      *       * @param context      *            can start activity      */     public static void rungpsstatus(context context) {         intent intent = new intent(intent.action_main);         intent.setcomponent(new componentname(gps_status_package_name, gps_status_class_name));         list list = context.getpackagemanager().queryintentactivities(intent, packagemanager.component_enabled_state_default);          if (list.size() > 0) {             // have application             context.startactivity(intent);         } else {             // none application         }     }