尝试将kotlin方法转换为使用RxJava的java

Question

Android Studio 3.1 RC 2
kotlin 1.2.30

fetchMessage的签名

Single<Response> fetchMessage(final String messageId);

我试图转换为Java的kotlin代码。但是，我不确定回报在哪里？因为我是kotlin和lambda的新手。

private fun getMessage(messageId: String): Observable<State> {
        return repository
                .fetchMessage(messageId)
                .flatMap {
                    Single.fromCallable<State>({
                        update(messageId, it, State.COMPLETED)
                        State.COMPLETED
                    })
                }
                .toObservable()
}

这是我尝试转换它的尝试。但是，编译器抱怨缺少返回。

public Observable<TranslationChatState> translate(String messageId) {
        return repository
                .fetchMessage(messageId)
                .flatMap(new Func1 <Response, Single<State >>() {
                    @Override
                    public Single<State> call(final Response response) {
                        Single.fromCallable(new Callable<State>() {
                            @Override
                            public State call() {
                                update(messageId, response, State.COMPLETED);
                                return State.COMPLETED;
                            }
                        });
                    } /* complains about no return here */
                })
                .toObservable();
}

非常感谢任何建议，

Answer 1

因为它缺少return语句。它应该是

public Single<State> call(final Response response) {
     return Single.fromCallable(new Callable<State>() {