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google/guava

🔥 Hot★ 51,499JavaAudience · developerComplexity · 2/5ActiveLicenseSetup · easy

TLDR

Google's collection of utility libraries that fill gaps in Java's standard library, providing better collections, string tools, caching, hashing, and concurrency helpers.

Mindmap

mindmap
  root((Guava))
    What it does
      Collections utilities
      String manipulation
      Caching layer
      Hashing tools
    Collections types
      Multimap
      Multiset
      Immutable collections
      Graph library
    Use cases
      Avoid writing helpers
      Thread-safe sharing
      Parallel code
      File operations
    Tech stack
      Java 8 plus
      Android variant
      Maven or Gradle

Things people build with this

USE CASE 1

Add a multimap or multiset to your Java project instead of building one from scratch.

USE CASE 2

Cache expensive computation results to avoid recalculating them on every request.

USE CASE 3

Split and join strings, pad text, or format output without verbose boilerplate.

USE CASE 4

Compute hashes and checksums using a clean, consistent API across your codebase.

Tech stack

JavaMavenGradle

Getting it running

Difficulty · easy Time to first run · 5min
Use freely for any purpose, including commercial use, as long as you keep the copyright notice and license text.

In plain English

Guava is Google's open-source collection of core utility libraries for the Java programming language. Java's standard library covers many basics, but Guava fills in important gaps that Java developers encounter repeatedly in real projects, areas where the built-in tools are either absent, awkward, or verbose. The library covers a wide range of everyday programming needs. For collections, Guava adds types that Java's standard library lacks: a multimap (a map where each key can have multiple values), a multiset (a set that counts duplicates), immutable (unchangeable) versions of standard collections that are safe to share across threads, and a graph library for working with nodes and edges. Beyond collections, Guava provides utilities for string manipulation (splitting, joining, padding, formatting), hashing (computing checksums and fingerprints using a clean API), caching (storing computed results temporarily to avoid re-computing them), working with files and streams, and handling concurrency, the tricky business of running code in parallel. You would use Guava whenever you are writing Java code and find yourself about to write a utility helper from scratch, chances are Guava already has a well-tested, well-maintained version. It is one of the most widely used third-party Java libraries in the industry, used heavily at Google internally and by countless other companies. Guava is added to a project as a single dependency via Maven or Gradle (the two most common Java build tools). It comes in two variants: one for standard Java 8 and above, and one for Android development. The tech stack is pure Java. There is no framework dependency, Guava is a library you add to your project, not a platform or runtime.

Copy-paste prompts

Prompt 1
Show me how to use Guava's Multimap to store multiple values per key in Java.
Prompt 2
How do I create an immutable copy of a list in Guava and why is it thread-safe?
Prompt 3
Write a Java example using Guava's caching to store results of an expensive function call.
Prompt 4
How do I use Guava's Joiner and Splitter to handle string manipulation cleanly?
Prompt 5
Add Guava to my Maven project and show me a simple example of using its utilities.
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