multithreading - How to start a thread after specified time delay in java

Question

I have called a method in ServletContextListener as thread ..Now as per my need i have to delay the thread for 1 minutes and then start executing the method called in the thread but i am not able to do that as i am very new in this...

Here is my code ...

public class Startup implements ServletContextListener {

@Override
public void contextDestroyed(ServletContextEvent sce) {
}

public void contextInitialized(ServletContextEvent sce) {
    // Do your startup work here
    System.out.println("Started....");
    //captureCDRProcess();
    new Thread(new Runnable() {

        @Override
        public void run() {

            captureCDRProcess();
        }
    }).start();

}

Please help me .. Thanks in advance..

Answer 1

To do this properly, you need to use a ScheduledThreadPoolExecutor and use the function schedule like this:

final ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(NUM_THREADS);
executor.schedule(new Runnable() {
  @Override
  public void run() {
    captureCDRProcess();
  }
}, 1, TimeUnit.MINUTES);

Thread.sleep is not the way to go, because it does not guarantee that it wakes up after a minute. Depending on the OS and the background tasks, it could be 60 seconds, 62 seconds or 3 hours, while the scheduler above actually uses the correct OS implementation for scheduling and is therefore much more accurate.

In addition this scheduler allows several other flexible ways to schedule tasks like at a fixed rate or fixed delay.

Edit: Same solution using the new Java8 Lamda syntax:

final ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(NUM_THREADS);
executor.schedule(() -> captureCDRProcess(), 1, TimeUnit.MINUTES);