Difference between future and completablefuture
 

Future
The Future API was introduced in Java 5 to reference the result of an asynchronous computation. However, it didn't have any methods to combine computations or handle errors.

CompletableFuture
The CompletableFuture class was introduced in Java 8. It implements the Future and CompletionStage interfaces, and provides a set of methods for creating, chaining, and combining multiple Futures.