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public interface ExecutorService extends Executor

An Executor that provides methods to manage termination and methods that can produce a Future for tracking progress of one or more asynchronous tasks.

The following example includes two classes. PrintTask.java creates threads that sleep for a random time (0-5 secs). RunnableTester.java executes the PrintTask threads using a fixed thread pool.

/*
* Runnables are executed by an object of a class that implements the Executor interface.
* This interfaces declares the method execute(Runnable). This method creates a new thread
* and launches it immediately.
*/
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;

public class RunnableTester
{
public static void main(String[] args)
{
// create and name each runnable
PrintTask task1 = new PrintTask("thread1");
PrintTask task2 = new PrintTask("thread2");
PrintTask task3 = new PrintTask("thread3");

System.out.println("Starting threads");

// create ExecutorService to manage threads
ExecutorService threadExecutor = Executors.newFixedThreadPool(3);

// start threads and place in runnable state
threadExecutor.execute(task1); // start task1
threadExecutor.execute(task2); // start task2
threadExecutor.execute(task3); // start task3

threadExecutor.shutdown(); // shutdown worker threads

System.out.println("Threads started, main ends\n");
} // end main
} // end class RunnableTester

import java.util.Random;

class PrintTask implements Runnable
{
private int sleepTime; // random sleep time for thread

private String threadName; // name of thread

private static Random generator = new Random();

// assign name to thread
public PrintTask(String name)
{
threadName = name; // set name of thread

// pick random sleep time between 0 and 5 seconds
sleepTime = generator.nextInt(5000);
} // end PrintTask constructor

{
// TODO Auto-generated constructor stub
}

// method run is the code to be executed by new thread
public void run()
{
try
// put thread to sleep for sleepTime amount of time
{
System.out.printf("%s going to sleep for %d milliseconds.\n",
threadName, sleepTime);

Thread.sleep(sleepTime); // put thread to sleep
} // end try
// if thread interrupted while sleeping, print stack trace
catch (InterruptedException exception)
{
exception.printStackTrace();
} // end catch

// print thread name
System.out.printf("%s done sleeping\n", threadName);
} // end method run
} // end class PrintTask