While developing applications, you may face such a situation where you may need to accumulate and consolidate emissions. Note that nearly all the operators under this criteria will only work on a finite producer (Observable/Flowable) that calls onComplete() because typically, we can consolidate only finite datasets. We will explore this behavior as we cover these operators.

Here is a short list of reducing operators, which we will cover in this chapter:

• count
• reduce
• all
• any
• contains