Java Concurrency Uncovered — Part 8: CompletableFuture — Execution & Result Processing

Explore how asynchronous tasks are launched, how results flow through successive stages, and how follow-up actions can be triggered without blocking.

To improve responsiveness and scalability, enterprise and distributed applications often need to execute multiple asynchronous operations in the background while continuing with other processing.

Callable, Future, and FutureTask support asynchronous execution, but coordinating the results can become difficult. With Future, retrieving a result may block the calling thread, while chaining dependent tasks or coordinating multiple asynchronous operations requires additional code.

Java 8 introduced CompletableFuture to simplify non-blocking asynchronous workflows. This part focuses on executing asynchronous tasks and processing their results, followed by task composition in Part 9 and exception handling in Part 10.

Introducing CompletableFuture

CompletableFuture, introduced in Java 8, implements both Future and CompletionStage — combining the ability to represent an asynchronous computation with support for chaining, combining, and…