Java concurrency - avoid busy wait using ExecutorService and Future

import com.google.common.util.concurrent.ThreadFactoryBuilder;

​

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

import java.util.concurrent.TimeUnit;

​

public class TaskExecutorWithFuture {

​

    private final ExecutorService executor = Executors.newFixedThreadPool(2,

            new ThreadFactoryBuilder().setNameFormat("task-executor-%d").build()

    );

​

    private void executeTasks() throws InterruptedException, ExecutionException {

​

        Future<String> task1 = executor.submit(() -> {

            simulateTask(300);

            System.out.println(getThreadName() + " - Task 1 done");

            return "Results from task 1";

        });

​

        Future<String> task2 = executor.submit(() -> {

            simulateTask(100);

            System.out.println(getThreadName() + " - Task 2 done");

            return "Results from task 2";

        });

​

        System.out.println(getThreadName() + " - waiting for 2 tasks to be completed");

        String result1 = task1.get();

        String result2 = task2.get();

        System.out.println(getThreadName() + " - 2 tasks done");

​

        executor.shutdown();

    }

​

    private String getThreadName() {

        return Thread.currentThread().getName();

    }

​

    private void simulateTask(int timeout) {

        sleep(timeout);

    }

​

    private void sleep(int timeout) {

        try {

            TimeUnit.MILLISECONDS.sleep(timeout);

        } catch (InterruptedException e) {

            e.printStackTrace();

        }

    }

​

    public static void main(String[] args) throws InterruptedException, ExecutionException {

        new TaskExecutorWithFuture().executeTasks();

    }

}

main - waiting for 2 tasks to be completed

task-executor-1 - Task 2 done

task-executor-0 - Task 1 done

main - 2 tasks done