Java 8 CompletableFuture parallel tasks and Timeout example

CompletableFutureTimeout.java

package com.company;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * Created by sunels on 02.12.2018.
 */
public class CompletableFutureTimeout {
    public static void main (String[] args) {
        int numOfParallelTasks = 10;
        long startTime = System.currentTimeMillis ();
        ExecutorService es = Executors.newFixedThreadPool (numOfParallelTasks);
        List<CompletableFuture> futures = new ArrayList<> ();
        CompletableFutureTimeout r = new CompletableFutureTimeout ();
        for (long i = 0; i < numOfParallelTasks; i++) {
            final long sleepDuration = i * 1000l;
            CompletableFuture<String> future = CompletableFuture.supplyAsync (() -> r.doSomeSleep (sleepDuration), es);
            futures.add (future);
        }

        System.out.println ("Duration here = " + (System.currentTimeMillis () - startTime));
        try {
            Thread.currentThread ().sleep (5000l);
        } catch (InterruptedException e) {
        }

        List<Object> resultArray = new ArrayList<> ();

        for (int i = 0; i < numOfParallelTasks; i++) {
            Object result = futures.get (i).getNow (null);
            resultArray.add (result);
        }

        es.shutdown ();
        try {
            if (!es.awaitTermination (1l, TimeUnit.NANOSECONDS)) {
                es.shutdownNow ();
            }
        } catch (InterruptedException e) {
            es.shutdownNow ();
        }

        System.out.println ("Collected Results = " + resultArray);
        System.out.println ("Total Duration = " + (System.currentTimeMillis () - startTime));
    }

    public String doSomeSleep (long sleep) {
        String result;
        try {
            Thread.sleep (sleep);
            System.out.println (Thread.currentThread ().getName () + " - - > will sleep for secs :" + sleep);
            result = sleep + "";
        } catch (Exception e) {
            result = e.getMessage ();
        }
        return result;
    }

}