//  Clock.java  (c) 2005 Kari Laitinen

//  http://www.naturalprogramming.com

//  2004-09-26  File created.
//  2005-05-15  Last modification.

/*  In this program the interrupt() method is used to stop
    the Thread.sleep() operations. In addition, the 
    stop_this_thread() methods are called to ensure that the
    threads stop. It is likely that this program would work
    without the stop_this_thread() methods.
*/

import java.util.* ;

class  ThreadToShowSeconds  extends  Thread
{
   boolean  must_show_seconds  =  true ;

   public void stop_this_thread()
   {
      must_show_seconds  =  false ;
   }

   public void run()
   {
      while ( must_show_seconds  ==  true )
      {
         Calendar  date_and_time_now  =  new  GregorianCalendar() ;

         int seconds_of_current_time  =
                          date_and_time_now.get( Calendar.SECOND ) ;

         if ( ( seconds_of_current_time  %  20 )  ==  0 )
         {
            System.out.print( "\n" ) ;
         }

         System.out.printf( " %02d", seconds_of_current_time ) ;

         try
         {
            Thread.sleep( 1000 ) ; // Delay of one second.
         }
         catch ( InterruptedException caught_exception )
         {
            must_show_seconds  =  false ;
         }
      }
   }
}


class  ThreadToShowFullTimeInfo  extends  Thread
{
   boolean  must_show_full_time_info  =  true ;

   public void stop_this_thread()
   {
      must_show_full_time_info  =  false ;
   }

   public void run()
   {
      Calendar  date_and_time_now  =  new  GregorianCalendar() ;

      int  seconds_to_first_time_printing  =
                  60  -  date_and_time_now.get( Calendar.SECOND ) ;

      try
      {
         Thread.sleep( seconds_to_first_time_printing * 1000 ) ;
      }
      catch ( InterruptedException caught_exception )
      {
         must_show_full_time_info  =  false ;
      }

      while ( must_show_full_time_info  ==  true )
      {
         date_and_time_now  =  new  GregorianCalendar() ;

         System.out.printf( "\n\n %tT \n\n", date_and_time_now ) ;

         try
         {
            Thread.sleep( 60000 ) ; // Delay of 60 seconds.
         }
         catch ( InterruptedException caught_exception )
         {
            must_show_full_time_info  =  false ;
         }
      }
   }
}


class Clock
{
   public static void main( String[] not_in_use )
   {
      Scanner keyboard = new Scanner( System.in ) ;

      ThreadToShowSeconds thread_to_show_seconds  = 
                                           new ThreadToShowSeconds() ;

      ThreadToShowFullTimeInfo thread_to_show_full_time_info  =
                                      new ThreadToShowFullTimeInfo() ;

      System.out.print( "\n Press the Enter key to stop the clock.\n\n" ) ;

      thread_to_show_seconds.start() ;
      thread_to_show_full_time_info.start() ;

      String  any_string_from_keyboard  =  keyboard.nextLine() ;

      thread_to_show_seconds.stop_this_thread() ;
      thread_to_show_full_time_info.stop_this_thread() ;
      thread_to_show_seconds.interrupt() ;
      thread_to_show_full_time_info.interrupt() ;
   }
}