class Person {

        public String firstName;
        public String lastName;
        public String fullName;

        @Override
        public String toString() {
            return firstName + " " + lastName;
        }

        public Person(String firstName, String lastName) {
            this.firstName = firstName;
            this.lastName = lastName;

        }

    }

    private static Person renamePerson(Person p) {
        p.fullName = p.firstName + " : " + p.lastName;
        return p;

    }


    @Test
    public void testMap() {

        final ThreadFactory threadFactory = new ThreadFactoryBuilder()
                .setNameFormat("Поток-%d")
                .setDaemon(true)
                .build();

        final ExecutorService es = Executors.newFixedThreadPool(2, threadFactory);

        List<Person> persons = Arrays.asList(new Person("1", "2"), new Person("3", "4"));




//1
        CompletableFuture[] futures
                = 
                        persons.stream()
                        .map(p -> CompletableFuture.supplyAsync(
                        () -> renamePerson((Person) p), es))
                        .map(f -> f.thenAccept(System.out::println))
                        .toArray(size -> new CompletableFuture[size]);
//2
        CompletableFuture.allOf(futures).join();
        
             
 //3    тут сохраняем в базу 
        persons.stream().forEach(p -> System.out.println(p.fullName));