title: How to know Runnable scheduled for repeated execution
body: <p>I need to run five thread to fetch data from API repeatedly each 20 second ,so I used ScheduledExecutorService.    </p>
  
  <pre><code>ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(5);
  
  for (int i = 0; i &lt; 5; i++) {
      scheduler.scheduleWithFixedDelay(Constant.workerThread[i], 0, delay, TimeUnit.SECONDS);
  }
  </code></pre>
  
  <p>How can I know (at each time) when the five threads are executed?</p>