title: Difference between a Future and a Mono
body: <p>In (Java) reactive programming, what is the difference between a <a href="https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/Future.html" rel="noreferrer"><code>Future&lt;T&gt;</code></a> and a (<a href="https://projectreactor.io/" rel="noreferrer">Project Reactor</a>) <a href="https://projectreactor.io/docs/core/release/api/reactor/core/publisher/Mono.html" rel="noreferrer"><code>Mono&lt;T&gt;</code></a>? Both seem to be means for accessing the result of an asynchronous computation at a time in the future when the computation is complete. Why introduce the <code>Mono</code> interface if <code>Future</code> already does the job?</p>