//
// simple example of threads in Java, showing interleaving of actions
//      from two independent threads
//
// in this version, thread objects are created using a class that
//      implements the Runnable interface (compare with 
//      SimpleThread.java, which behaves the same but is implemented
//      slightly differently).
//
// see main method below for command-line arguments.
//

//
// a SimpleThreadObj object, when executed by a thread, repeatedly 
//      prints message msg and then sleeps for sleepIntvl milliseconds.
//
public class SimpleThreadObj implements Runnable {

        String msg ;
        long sleepIntvl ;
        int cycles ;

        SimpleThreadObj(String m, int s, int c) {
                msg = m ;
                sleepIntvl = (long) s ;
                cycles = c ;
        }

        // implements run() in Runnable interface to define object's
        //      behavior.
        public void run() {
                try {
                        for (int i = 0 ; i < cycles ; i++) {
                                System.out.println(msg) ;
                                Thread.sleep(sleepIntvl) ;
                                // note this change
                        }
                // can safely ignore interrupts here -- should not
                //      happen in this program
                } catch (InterruptedException e) {
                }
        }

        // command-line arguments are integers S1, S2, C.
        // builds and starts two threads using SimpleThreadObj
        //      objects, with sleep intervals of S1 and S2.  observe 
        //      the difference in execution behavior when S1 and S2 are 
        //      the same and when they are different.
        // continues for C cycles.

        public static void main(String[] args) {

                if (args.length < 3) {
                        System.out.println("Arguments are:") ;
                        System.out.println("  sleep interval for t1") ;
                        System.out.println("  sleep interval for t2") ;
                        System.out.println("  cycles") ;
                        System.exit(-1) ;
                }

                int S1 = Integer.parseInt(args[0]) ;
                int S2 = Integer.parseInt(args[1]) ;
                int C = Integer.parseInt(args[2]) ;

                Thread t1 = new Thread(
                        new SimpleThreadObj("ping---->", S1, C)) ;
                Thread t2 = new Thread(
                        new SimpleThreadObj("<----pong", S2, C)) ;

                t1.start() ;
                t2.start() ;
        }
}