flatmap rxjava发送消息接受不到

     Observable<Object> o = Observable.create(new ObservableOnSubscribe<Object>() {
            @Override
            public void subscribe(@NotNull ObservableEmitter<Object> emitter) throws Exception {
                emitter.onNext("发送接受");
                emitter.onComplete();
            }
        });

        o.flatMap(new Function<Object, ObservableSource<String>>() {
            @Override
            public ObservableSource<String> apply(@NotNull Object o) throws Exception {
                return Observable.just("1111");
            }
        }).subscribe(new Observer<String>() {
            @Override
            public void onSubscribe(@NotNull Disposable d) {

            }

            @Override
            public void onNext(@NotNull String s) {
                System.out.println(s);

            }

            @Override
            public void onError(@NotNull Throwable e) {

            }

            @Override
            public void onComplete() {
                System.out.println("onComplete");
            }
        });

    }

打印消息
1111
onComplete
当你把 o中的

                emitter.onNext("发送接受");

删除，你将只能收到 打印消息
onComplete