Tickers in CLIPS

Java provides a similar mechanism to tickers through the ScheduledExecutorService class. Here’s an example that demonstrates periodic execution at regular intervals:

import java.util.concurrent.*;

public class Tickers {
    public static void main(String[] args) throws InterruptedException {
        // Create a ScheduledExecutorService with a single thread
        ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);

        // Schedule a task to run every 500 milliseconds
        ScheduledFuture<?> ticker = scheduler.scheduleAtFixedRate(() -> {
            System.out.println("Tick at " + System.currentTimeMillis());
        }, 0, 500, TimeUnit.MILLISECONDS);

        // Let it run for 1600 milliseconds (should tick 3 times)
        Thread.sleep(1600);

        // Cancel the ticker
        ticker.cancel(false);
        scheduler.shutdown();

        System.out.println("Ticker stopped");
    }
}

In this example, we use a ScheduledExecutorService to create a ticker that runs every 500 milliseconds. The scheduleAtFixedRate method is used to schedule a task that prints the current time.

We let the ticker run for 1600 milliseconds, which should allow it to tick 3 times. After that, we cancel the ticker and shut down the scheduler.

When we run this program, the ticker should tick 3 times before we stop it:

$ javac Tickers.java
$ java Tickers
Tick at 1623456789000
Tick at 1623456789500
Tick at 1623456790000
Ticker stopped

The ScheduledExecutorService in Java provides a flexible way to schedule tasks to run periodically. Unlike Go’s ticker, which uses channels, Java uses a more traditional approach with threads and scheduling. The scheduleAtFixedRate method ensures that the task is executed repeatedly at the specified interval.

Remember to always shut down the ScheduledExecutorService when you’re done with it to release the resources and allow the program to exit cleanly.