Start 5 tasks and wait until they finish

TaskExecutor.java

package com.guilherme.miguel;

import io.vavr.control.Try;
import lombok.extern.slf4j.Slf4j;

import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

import static java.lang.String.format;

@Slf4j
public class TaskExecutor {

    public static void main(String[] args) {

        ExecutorService executorService = Executors.newFixedThreadPool(5);

        // Create 5 Tasks
        List<Future<String>> futures = IntStream.rangeClosed(1, 5)
                .mapToObj(i -> executorService.submit(() -> doTask(i)))
                .collect(Collectors.toList());

        // Wait until everything finishes
        log.info("Waiting for everything to finish...");
        List<String> list = futures.stream()
                .map(i -> Try.of(() -> i.get()).getOrElse(""))
                .collect(Collectors.toList());
        
        executorService.shutdown();

        log.info("Done...");
        list.forEach(i -> log.info(i.toString()));
    }


    /**
     * Dummy Task
     */
    private static String doTask(int i) {

        log.info("Start Task {}", i);
        Try.run(() -> Thread.sleep((long) (Math.random() * 5000)));
        log.info("End Task {}", i);

        return format("Task %s", i);
    }
}

// Expected Result

// [pool-1-thread-2] INFO com.guilherme.miguel.TaskExecutor - Start Task 2            
// [pool-1-thread-3] INFO com.guilherme.miguel.TaskExecutor - Start Task 3            
// [pool-1-thread-4] INFO com.guilherme.miguel.TaskExecutor - Start Task 4            
// [main] INFO com.guilherme.miguel.TaskExecutor - Waiting for everything to finish...
// [pool-1-thread-5] INFO com.guilherme.miguel.TaskExecutor - Start Task 5            
// [pool-1-thread-1] INFO com.guilherme.miguel.TaskExecutor - Start Task 1            
// [pool-1-thread-5] INFO com.guilherme.miguel.TaskExecutor - End Task 5              
// [pool-1-thread-2] INFO com.guilherme.miguel.TaskExecutor - End Task 2              
// [pool-1-thread-1] INFO com.guilherme.miguel.TaskExecutor - End Task 1              
// [pool-1-thread-4] INFO com.guilherme.miguel.TaskExecutor - End Task 4              
// [pool-1-thread-3] INFO com.guilherme.miguel.TaskExecutor - End Task 3              
// [main] INFO com.guilherme.miguel.TaskExecutor - Done...                            
// [main] INFO com.guilherme.miguel.TaskExecutor - Task 1                             
// [main] INFO com.guilherme.miguel.TaskExecutor - Task 2                             
// [main] INFO com.guilherme.miguel.TaskExecutor - Task 3                             
// [main] INFO com.guilherme.miguel.TaskExecutor - Task 4                             
// [main] INFO com.guilherme.miguel.TaskExecutor - Task 5