NEVER MULTI-THREAD YOUR SYSTEM CLOCK

THE BREEZE SECTION.

If three men have to pass through a door that can take only one, how many men can pass through at any one time?

“Hey, you? ”

“One.”

“Why one?”

That's the question, why only one? Can't they piggyback through the door, like the one in front having another on his back and another on his back and another ad infinitum, provided the height of the door can accommodate as many? Well, convention and dynamism are two ends of the same stick. The longer one stays it becomes the other.

Now before we enter the door of seriosity, I'll like to unwind with a cup of Chinese tea. I like the ginseng blend. Which do you prefer? Choose yours.

I had this question thrown to me recently: How can one implement three threads such that they reference the same time while preventing deadlock and other issues known with threads.

What would you answer? As they always say, KISS. Keep it simple, stupid. So I decided to write a simple class that displays just one time, just one thread, my system time converted to UTC time. Foremost on my mind was what the thread was going to do: simple, just update my system time, convert it to Universal Time and format it in a simple human-readable format.

import java.text.DateFormat;
import java.util.*;
import java.lang.*;

public class Availables implements Runnable {
    
    DateFormat firstFormatter; 
    
    public void run() {
        //get my present instance
        Date date = new Date();
        //an a simple utc time zone converter
        SimpleTimeZone utcZone = new SimpleTimeZone(0, "UTC");
        //i don't want this timer to run just five minutes
        final long LIMIT = 1000*60*5;
        //then i'll set a time guard on our time
        long timeSpent = 0;
        //while the thread is running, i expect to receive an 
        //interrupted exception. maybe from my puter
        try{
            //what next? until five minutes runs out
            while(timeSpent < LIMIT){
                //set the time zone for our time
                firstFormatter = DateFormat.getTimeInstance();
                firstFormatter.setTimeZone(utcZone);
                //print out what the present time is
                System.out.println(firstFormatter.format(new Date()));
                //ask the thread to sleep for 3s seconds, to
                //simulate a real timer
                Thread.sleep(1000*3);
                //update our thread, compute the elapsed time
                Date now = new Date();
                timeSpent = now.getTime()- date.getTime();
            }
        }
        catch(InterruptedException e){
            e.printStackTrace();
        }
        //little checker. unecessary, but you never can tell
        if (Thread.interrupted()){System.out.println("Finished.");}
    }
    
    public static void main(String[] args){
        Availables newbie = new Availables();
        Thread tre = new Thread(newbie);
        tre.start();
    }
}

Now, how about the other threads that had to show different time zones, say Hawaii standard time or New Zealand Standard Time? And to talk of Hawaii, if you had to choose between a special Home in Florida and a week in Hawaii, which would it be. I saw this lovely house, and my, did i fall in love with it. Would you still go to Hawaii?