Java: execute Runnable fixed number of times

Question

So I have a piece of code that I want to execute repeatedly. I get this part. The problem is that I want to execute the code at fixed intervals, but only a fixed number (in this case 1440) times.

Any ideas how I'd do that?

Here's the code:

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;


public class Simulator {

    public static int TICK = 10;
    public static int NUM_OF_SERVERS = 3;
    public static int LENGTH_OF_SIMULATION = 1440;

    public static void main(String[] args) {


        final MultiQueueControlSystem multiController = MultiQueueControlSystem.getInstance();
        final SingleQueueControlSystem singleController = SingleQueueControlSystem.getInstance();

        multiController.generateQueuesAndServers(NUM_OF_SERVERS);
        singleController.generateQueuesAndServers(NUM_OF_SERVERS);

        final ScheduledExecutorService ticker = Executors.newSingleThreadScheduledExecutor();

        ticker.scheduleAtFixedRate(new Runnable() {

            int currentTime = 0;

            public void run() {

                if(currentTime < LENGTH_OF_SIMULATION) {
                    currentTime = currentTime + 1;
                } else {
                    ticker.shutdown();
                    return;
                }

                multiController.customerArrival();
                multiController.allocateCustomersToServers();
                multiController.removeFinishedCustomersFromServers();

                singleController.customerArrival();
                singleController.allocateCustomersToServers();
                singleController.removeFinishedCustomersFromServers();
            }
        }, 1, TICK, TimeUnit.MILLISECONDS);
    }
}

@user2418306 Yeah I know. Someone else wrote most of the code. But yeah, that's why I'm asking the question -- it doesn't work! :) — Ben Lawton, Apr 18 '15 at 17:01
I'm sorry. Actually `SceduledExecutorService` do preserve state of the `Runnable` at least on my JVM implementation. Code above works for me. — user2418306, Apr 18 '15 at 17:33
The above code works for me as well. The currentTime value is preserved. — Nithish Thomas, Apr 18 '15 at 17:36

score 1 · Accepted Answer · answered Apr 18 '15 at 16:51

1

Consider giving your runnable a reference to the ScheduledExecutorService. Then instead of scheduling at a fixed rate, just schedule for future execution. Have the runnable instance keep tracker (through an AtomicInteger) how many times it has been executed. When it completes it's normal execution it can schedule itself for future execution. Once it has executed the desired number of times, it would not schedule itself again.

answered Apr 18 '15 at 16:51

Brett Okken

6,210
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This is humorous (but angry) commentary on the [ScheduledExecutorService](http://code.nomad-labs.com/2011/12/09/mother-fk-the-scheduledexecutorservice/) and how to get it to behave. LOL. Worth a quick glance. – Apr 18 '15 at 17:01

score 0 · Answer 2 · answered Apr 18 '15 at 17:02

0

try this

Take any integer variable runCount (increment after every cycle) and service the object returned from scheduleAtFixedRate method

if(runCount == LENGTH_OF_SIMULATION ) { service.cancel(false); }

answered Apr 18 '15 at 17:02

gursahib.singh.sahni

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Java: execute Runnable fixed number of times

2 Answers2