CompletableFuture vs Future in Java: A Comprehensive Comparison

source : stackoverflow.com/

Concurrency is a core aspect of Java programming, and understanding the tools available for handling asynchronous tasks is crucial. Two important classes for this purpose are Future and CompletableFuture. This article will walk you through the differences between these two, using plenty of code examples to illustrate key concepts.

Introduction

In Java, managing asynchronous tasks can be handled using various classes, among which Future and CompletableFuture are prominent. While Future has been around since Java 5, CompletableFuture was introduced in Java 8 to address some limitations and provide a more comprehensive approach to asynchronous programming. Let's dive into each and see how they compare.

What is a Future?

A Future represents the result of an asynchronous computation. Methods are provided to check if the computation is complete, wait for its completion, and retrieve the result. However, Future has limitations, such as:

• No built-in way to handle completion callbacks.
• Blocking operations to get the result.
• Difficult to compose multiple asynchronous computations.