Scheduled Executor Service

Executor can return Executor, ExecutorService, and ScheduledExecutorService.

This is very, very usful Tiger new timer.

 

scheduler.scheduleAtFixedRate(new TimePrinter(System.out), 0, 10, SECONDS);

4 arguments:

1) Runable or Callable, which is the task scheduled to run.

2) 0. When the first time to run. 0 seconds later, means, immediately.

3) 10. When next time run. 10 seconds later.

4) What's time unit. The argument 0, and 10, all use the time unit SECONDs.

 

 

package test;

 

import java.io.PrintStream;

import java.util.Date;

import java.util.concurrent.Executors;

import java.util.concurrent.ScheduledExecutorService;

import java.util.concurrent.ScheduledFuture;

import static java.util.concurrent.TimeUnit.SECONDS;;

 

public class Thread5

{

      public static void main(String[] args)

      {

 

            // Get the scheduler

            //An alternative way to get scheduler is like this, you can simply replace with it

            //ScheduledThreadPoolExecutor scheduler = new ScheduledThreadPoolExecutor(10);

            ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();

 

            // Get a handle, starting now, with a 10 second delay

            final ScheduledFuture<?> timeHandle = scheduler.scheduleAtFixedRate(new TimePrinter(System.out), 0, 10, SECONDS);

 

            // Schedule the event, and run for 1 hour (60 * 60 seconds)

            scheduler.schedule(new Runnable()

            {

                  public void run()

                  {

                        timeHandle.cancel(false);

                  }

            }, 60 * 60, SECONDS);

 

      }//end of main

}

 

class TimePrinter implements Runnable

{

      private PrintStream out;

 

      public TimePrinter(PrintStream out)

      {

            this.out = out;

            System.out.println("a TimePrinter instance is created");

      }

 

      public void run()

      {

            out.printf("Current time: %tr%n", new Date());

      }

}

 

 

 

 

 

 

 

 

Summary:

 

Step 1) Get a ScheduledExecutorService --- Scheduler
Step 2) Tell the scheduler, which to run, how frequent, when to start. ---generate ScheduledFuture
Step 3) Start the Scheduler using schedule() method, wraping ScheduledFuture into Runnable, passing the Runnable to the schedule()