src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.CUSTOM)
    public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
            Scheduler scheduler, long count) {
        return window(timespan, unit, scheduler, count, false);
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.CUSTOM)
    public final Observable<Observable<T>> window(long timespan, TimeUnit unit,
            Scheduler scheduler, long count) {
        return window(timespan, unit, scheduler, count, false);
    }
@ CheckReturnValue @ SchedulerSupport ( SchedulerSupport . CUSTOM ) public final Observable < Observable < T > > window ( long timespan , TimeUnit unit , Scheduler scheduler , long count ) { return window ( timespan , unit , scheduler , count , false ) ; }
Returns an Observable that emits windows of items it collects from the source ObservableSource. The resulting
ObservableSource emits connected, non-overlapping windows, each of a fixed duration specified by the
{@code timespan} argument or a maximum size specified by the {@code count} argument (whichever is reached
first). When the source ObservableSource completes or encounters an error, the resulting ObservableSource emits the
current window and propagates the notification from the source ObservableSource.
<p>
<img width="640" height="370" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/window6.s.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>You specify which {@link Scheduler} this operator will use.</dd>
</dl>

@param timespan
the period of time each window collects items before it should be emitted and replaced with a
new window
@param unit
the unit of time which applies to the {@code timespan} argument
@param count
the maximum size of each window before it should be emitted
@param scheduler
the {@link Scheduler} to use when determining the end and start of a window
@return an Observable that emits connected, non-overlapping windows of items from the source ObservableSource
that were emitted during a fixed duration of time or when the window has reached maximum capacity
(whichever occurs first)
@see <a href="http://reactivex.io/documentation/operators/window.html">ReactiveX operators documentation: Window</a>
Returns an Observable that emits windows of items it collects from the source ObservableSource . The resulting ObservableSource emits connected non - overlapping windows each of a fixed duration specified by the { @code timespan } argument or a maximum size specified by the { @code count } argument ( whichever is reached first ) . When the source ObservableSource completes or encounters an error the resulting ObservableSource emits the current window and propagates the notification from the source ObservableSource . <p > <img width = 640 height = 370 src = https : // raw . github . com / wiki / ReactiveX / RxJava / images / rx - operators / window6 . s . png alt = > <dl > <dt > <b > Scheduler : < / b > < / dt > <dd > You specify which { @link Scheduler } this operator will use . < / dd > < / dl >