# Future interface in Java

package com.exampe.java;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import java.util.concurrent.*;

@SpringBootApplication
public class DemoApplication {

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

		SpringApplication.run(DemoApplication.class, args);
        
		System.out.println("--------------------------------------------");

		Callable<Integer> callable1 = () -> {
		  {
			System.out.println("Callable #1 is running");
		  };
		  return 10;
		};

		Callable<Integer> callable2 = () -> {
		  {
			System.out.println("Callable #2 is running");
			Thread.sleep(3000);
		  };
		  return 20;
		};

		ExecutorService es = Executors.newFixedThreadPool(10);
		
		// Run a task (callable). The task has a result kept in the future object
		Future<Integer> f1 = es.submit(callable1);
		Future<Integer> f2 = es.submit(callable2);

        // block the current thread and get/wait the results of the 2 ASYNC calls
		Integer mySum = f1.get()+f2.get();
		System.out.println("Futures sum = "+mySum);
		
		// Stop the Executor Service
		es.shutdown();
		System.out.println("--------------------------------------------");
	}
}