android - 如何在没有任何延迟和第二个元素延迟的情况下获取第一个元素？

Question

 fun initScreenSaver(){
       Observable.fromCallable({GetScreenSaverUrlInteractor().execute() })
               .flatMapIterable{ urls-> urls }
               .zipWith(Observable.interval(10, TimeUnit.SECONDS), { item, interval -> item })
               .observeOn(AndroidSchedulers.mainThread())
               .subscribe(object : Subscriber<String>(){
                   override fun onNext(url: String?) {
                      view.loadImage(url)
                   }

                   override fun onCompleted() {
                       initScreenSaver()
                   }

                   override fun onError(e: Throwable?) {
                       TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
                   }

               })
   }

这里我尝试延迟 10 秒获取元素并加载到 ImageView 中。但是第一个元素应该立即出现。

Answer 1

Observable.interval() 有一个签名:

Observable<Long> interval(long initialDelay, long period, TimeUnit unit)

你可以这样使用它:

Observable.interval(0, 10, TimeUnit.SECONDS)

UPD

Observable.just ( listOf("Elem1", "Elem2", "Elem3", "Elem4") )
    .flatMapIterable{ urls -> urls }
    .zipWith<Long, String>(Observable.interval(0, 10, TimeUnit.SECONDS), BiFunction { t1, t2 ->  t1})
    .observeOn(AndroidSchedulers.mainThread())
    .doOnSubscribe { Log.d("DEBUG", "Start emitting")}
    .subscribe{Log.d("DEBUG", "item: $it")}

输出:

03-28 10:06:48.956 17086-17086/com.example.app D/DEBUG: Start emitting
03-28 10:06:49.633 17086-17086/com.example.app D/DEBUG: item: Elem1
03-28 10:06:58.957 17086-17086/com.example.app D/DEBUG: item: Elem2
03-28 10:07:08.957 17086-17086/com.example.app D/DEBUG: item: Elem3
03-28 10:07:18.957 17086-17086/com.example.app D/DEBUG: item: Elem4