Caffeine for Java: High-Performance In-Memory Cache

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What is it and why is it needed?

Caffeine is a high-performance in-memory caching library written in Java. It was created by Ben Manes and is one of the fastest cache implementations for the JVM. Caffeine is designed with modern multithreading requirements in mind and provides a rich API for managing the lifecycle of objects in the cache.

Why is Caffeine needed? In any application that works with data, a situation often arises where the same data is requested repeatedly. Instead of performing an expensive operation each time (database query, external API call, complex calculations), you can save the result in the cache. Caffeine does this as efficiently as possible, using the W-TinyLFU (Window Tiny Least Frequently Used) algorithm, which ensures high accuracy of element eviction and minimal overhead.

The library is actively used in large projects such as the Spring Framework (starting from version 5.0), where it is the standard cache implementation. Caffeine supports asynchronous loading, automatic record refresh, statistics, and many eviction strategies (by time, by size, by references).

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Installation

Caffeine is distributed via Maven Central. To use it, add the dependency to your pom.xml (Maven) or build.gradle (Gradle).

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Maven

<dependency>\n    <groupId>com.github.ben-manes.caffeine</groupId>\n    <artifactId>caffeine</artifactId>\n    <version>3.1.8</version>\n</dependency>

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Gradle

implementation 'com.github.ben-manes.caffeine:caffeine:3.1.8'

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For the latest version, check Maven Central.

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Quick Start

Minimal example of creating and using a Caffeine cache:

import com.github.benmanes.caffeine.cache.Cache;\nimport com.github.benmanes.caffeine.cache.Caffeine;\n\nimport java.util.concurrent.TimeUnit;\n\npublic class QuickStart {\n    public static void main(String[] args) {\n        // 1. Create a cache with a maximum size of 100 elements\n        //    and a record time-to-live of 10 minutes after last access\n        Cache<String, String> cache = Caffeine.newBuilder()\n                .maximumSize(100)\n                .expireAfterAccess(10, TimeUnit.MINUTES)\n                .build();\n\n        // 2. Put a value\n        cache.put("key1", "Hello, Caffeine!");\n\n        // 3. Get a value\n        String value = cache.getIfPresent("key1");\n        System.out.println(value); // Prints: Hello, Caffeine!\n\n        // 4. Get a value with a loading function (if key is absent)\n        String loadedValue = cache.get("key2", k -> "Loaded: " + k);\n        System.out.println(loadedValue); // Prints: Loaded: key2\n    }\n}

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Main Methods and Classes

Let's look at the key classes and methods of Caffeine. The main class for configuration is Caffeine, and for working with the cache — Cache, LoadingCache, and AsyncCache.

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