An Overview

An Overview

The following adapter is inspired by mattiwintou adapter from Rx Observable to F.Promise

https://gist.github.com/matiwinnetou/7b69253acaad996747c4

Benefits:

1. Code reuse
  - Future and CompletableFuture are part of Java 8 and thus ubiquitous
  - F.Promise only exist within the Play Framework
  - Using pure Java constructs means more flexible and compatibility with other frameworks

2. ReactiveX - Reactive Extensions
  - Rx Observables work seamlessly with Future and CompletableFuture

Example.java

public F.Promise<Result> rankedPairs() {
        CompletableFuture cf = ...
        return RxFutureAdapter.toPromise(cf).map(Controller::ok);
 }

RxFutureAdapter.java

package util;

import play.libs.F;

import java.util.concurrent.CompletableFuture;

public class RxFutureAdapter<T> {

    private final CompletableFuture<T> cf;

    public RxFutureAdapter(final CompletableFuture<T> cf) {
        this.cf = cf;
    }

    public static <E> F.Promise<E> toPromise(final CompletableFuture<E> obs) {
        return new RxFuture(obs).adopt();
    }

    public F.Promise<T> adopt() {
        F.RedeemablePromise<T> rPromise = F.RedeemablePromise.empty();
        cf.whenCompleteAsync((res, err) -> {
            if (err != null) {
                rPromise.failure(err);
            } else {
                rPromise.success(res);
            }
        });
        return rPromise;
    }
}