Difference between CompletableFuture, Future and RxJava's Observable

Question

I would like to know the difference between CompletableFuture,Future and Observable RxJava.

What I know is all a

Answer 1

All three interfaces serve to transfer values from producer to consumer. Consumers can be of 2 kinds:

• synchronous: consumer makes blocking call which returns when the value is ready
• asynchronous: when the value is ready, a callback method of the consumer is called

Also, communication interfaces differ in other ways:

• able to transfer single value of multiple values
• if multiple values, backpressure can be supported or not

As a result:

• Future transferes single value using synchronous interface

• CompletableFuture transferes single value using both synchronous and asynchronous interfaces

• Rx transferes multiple values using asynchronous interface with backpressure

Also, all these communication facilities support transferring exceptions. This is not always the case. For example, BlockingQueue does not.