CompletableFuture Java Implementation

Hello.java

package com.ustack.reactor.examples;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

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

        //With completable future example
        Hello hello = new Hello();
        Future<String> completableFuture = hello.calculateAsync();
        String result = completableFuture.get();
        System.out.println(result);

    }

    //Completable future implementation
    private Future<String> calculateAsync() {
        CompletableFuture<String> completableFuture = new CompletableFuture<>();
        Executors.newCachedThreadPool().submit(()->{
            Thread.sleep(1000);
            System.out.println("done wait");
            completableFuture.complete("hello");
            return null;
        });
        System.out.println("second");
        return completableFuture;
    }

}