如何访问传递到CompletableFuture的已完成期货？

Question

Promise.all([p1, p2]).then(function(persons) {
   console.log(persons[0]); // p1 return value     
   console.log(persons[1]); // p2 return value     
});

到目前为止我在Java方面的努力

public class Person {

        private final String name;

        public Person(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

    }

@Test
public void combinePersons() throws ExecutionException, InterruptedException {
    CompletableFuture<Person> p1 = CompletableFuture.supplyAsync(() -> {
        return new Person("p1");
    });

    CompletableFuture<Person> p2 = CompletableFuture.supplyAsync(() -> {
        return new Person("p1");
    });

    CompletableFuture.allOf(p1, p2).thenAccept(it -> System.out.println(it));

}

Answer 1

CompletableFuture#Allof方法不公开传递给它的已完成的CompletableFuture实例的集合。

返回一个新的completablefuture，该值在给定的completablefuture全部完成时完成。如果给定的CompletableFuture中的任何一个异常完成，则返回的CompletableFuture也会完成，其中CompletionException将此异常作为其原因。否则，给定的completablefuture的结果（如果有的话）不会反映在返回的completablefuture中，而是可以通过单独检查它们来获得。如果未提供completablefuture，则返回一个completablefuturecompleted值为null。

请注意，allof还将例外完成的期货视为已完成。因此，您并不总是需要与人员一起工作。您实际上可能有一个异常/可抛出。

CompletableFuture.allOf(p1, p2).thenAccept(it -> {
    Person person1 = p1.join();
    Person person2 = p2.join();
});

// make sure not to change the contents of this array
CompletableFuture<Person>[] persons = new CompletableFuture[] { p1, p2 };
CompletableFuture.allOf(persons).thenAccept(ignore -> {
   for (int i = 0; i < persons.length; i++ ) {
       Person current = persons[i].join();
   }
});

@Test
public Person[] combinePersons() throws Exception {
    CompletableFuture<Person> p1 = CompletableFuture.supplyAsync(() -> {
        return new Person("p1");
    });

    CompletableFuture<Person> p2 = CompletableFuture.supplyAsync(() -> {
        return new Person("p1");
    });

    // make sure not to change the contents of this array
    CompletableFuture<Person>[] persons = new CompletableFuture[] { p1, p2 };
    // this will throw an exception if any of the futures complete exceptionally
    CompletableFuture.allOf(persons).join();

    return Arrays.stream(persons).map(CompletableFuture::join).toArray(Person[]::new);
}