Guava: Google Core Libraries for Java

Guava is a set of core Java libraries from Google that includes new collection types
(such as multimap and multiset), immutable collections, a graph library, and
utilities for concurrency, I/O, hashing, caching, primitives, strings, and more! It
is widely used on most Java projects within Google, and widely used by many
other companies as well.

Guava comes in two flavors:

• The JRE flavor requires JDK 1.8 or higher.
• If you need support for Android, use the Android flavor. You can find the
  Android Guava source in the android directory.

Adding Guava to your build

Guava's Maven group ID is com.google.guava, and its artifact ID is guava.
Guava provides two different "flavors": one for use on a (Java 8+) JRE and one
for use on Android or by any library that wants to be compatible with Android.
These flavors are specified in the Maven version field as either 31.1-jre or
31.1-android. For more about depending on Guava, see
using Guava in your build.

To add a dependency on Guava using Maven, use the following:

<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>31.1-jre</version>
  <!-- or, for Android: -->
  <version>31.1-android</version>
</dependency>

To add a dependency using Gradle:

dependencies {
  // Pick one:

  // 1. Use Guava in your implementation only:
  implementation("com.google.guava:guava:31.1-jre")

  // 2. Use Guava types in your public API:
  api("com.google.guava:guava:31.1-jre")

  // 3. Android - Use Guava in your implementation only:
  implementation("com.google.guava:guava:31.1-android")

  // 4. Android - Use Guava types in your public API:
  api("com.google.guava:guava:31.1-android")
}

For more information on when to use api and when to use implementation,
consult the
Gradle documentation on API and implementation separation.

Snapshots and Documentation

Snapshots of Guava built from the master branch are available through Maven
using version HEAD-jre-SNAPSHOT, or HEAD-android-SNAPSHOT for the Android
flavor.

• Snapshot API Docs: guava
• Snapshot API Diffs: guava

Learn about Guava

• Our users' guide, Guava Explained
• A nice collection of
  other helpful links

Links

• GitHub project
• Issue tracker: Report a defect or feature request
• StackOverflow: Ask "how-to" and "why-didn't-it-work" questions
• guava-announce: Announcements of releases and upcoming significant changes
• guava-discuss: For open-ended questions and discussion

IMPORTANT WARNINGS

1. APIs marked with the @Beta annotation at the class or method level are
   subject to change. They can be modified in any way, or even removed, at any
   time. If your code is a library itself (i.e., it is used on the CLASSPATH of
   users outside your own control), you should not use beta APIs unless you
   repackage them. If your code is a library, we strongly recommend using
   the Guava Beta Checker to ensure that you do not use any @Beta APIs!

2. APIs without @Beta will remain binary-compatible for the indefinite
   future. (Previously, we sometimes removed such APIs after a deprecation
   period. The last release to remove non-@Beta APIs was Guava 21.0.) Even
   @Deprecated APIs will remain (again, unless they are @Beta). We have no
   plans to start removing things again, but officially, we're leaving our
   options open in case of surprises (like, say, a serious security problem).

3. Guava has one dependency that is needed for linkage at runtime:
   com.google.guava:failureaccess:1.0.1. It also has
   some annotation-only dependencies, which we discuss in more
   detail at that link.

4. Serialized forms of ALL objects are subject to change unless noted
   otherwise. Do not persist these and assume they can be read by a future
   version of the library.

5. Our classes are not designed to protect against a malicious caller. You
   should not use them for communication between trusted and untrusted code.

6. For the mainline flavor, we test the libraries using only OpenJDK 8 and
   OpenJDK 11 on Linux. Some features, especially in com.google.common.io,
   may not work correctly in other environments. For the Android flavor, our
   unit tests also run on API level 15 (Ice Cream Sandwich).