Hands-On Reactive Programming with Reactor

The reduce operator

The preceding section covered value accumulation, whereas the reduce operation revolves around value consolidation. The reduce method makes it possible to aggregate the complete data stream into a single value. This is depicted as follows:

Suppose that we want to generate a sum of Fibonacci numbers, as follows:

fibonacciGenerator.take(10).reduce((x,y) -> x+y).subscribe(t -> {
    System.out.println(t);
});

In the preceding code, we did the following things:

• The take operator selected the first 10 elements for the stream.
• The reduce operator took a Bifunction of the long type. The lambda expression returns the sum of the long ...