What is the Mono class in Java, and when should it be used?

General Discussions
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After using Reactor in a high-throughput system, here’s something worth noting—

One key clarification: java mono handles one (or no) result. But if you ever need to return multiple values—like a list or a stream—you’d switch to Flux.

Example for clarity:

Flux<Integer> numbers = Flux.just(1, 2, 3, 4);
Mono<Integer> singleValue = Mono.just(42);

So, TL;DR:

  • Use java mono for 0…1 reactive values.
  • Use Flux for 0…N values.

This distinction really matters when structuring APIs or database calls in reactive programming. Choosing the right one keeps your flow clean and predictable.