Archive for March, 2018

Java’s CompletableFuture and typed exception handling

With version 8, Java finally jumped on the asynchronous programming bandwagon with its own Promise-Oriented programming model, implemented by the CompletableFuture class and a set of interfaces and implementations it uses. The model is generally useful and not as horribly complicated as we sometimes get in the Java foundation class library(1), and it lends itself to fluent programming much better than the comparable model from fluent API proponent Vert.x project.

The Problem

One thing that most asynchronous computing models suffer from – and Java’s CompletableFuture is no exception – is the loss of typed exception handling. While CompletableFuture.exceptionally() is a good model that does not introduce a lot of boilerplate(2), you do lose the ability of the try..catch..finally syntax to effortlessly ignore exceptions you are not ready to handle and just letting them propagate up the stack. (more…)


  1. especially for things that claim to be “enterprise versions”, aughh []
  2. again, compare to Vert.x AsyncResult handlers. Other APIs, such as RX also do a good job in reducing boilerplate around error handling []

Spam prevention powered by Akismet