# Guava: Google Core Libraries for Java

[![Latest release](https://img.shields.io/github/release/google/guava.svg)](https://github.com/google/guava/releases/latest)
[![Build Status](https://travis-ci.org/google/guava.svg?branch=master)](https://travis-ci.org/google/guava)

Guava is a set of core libraries that includes new collection types (such as
multimap and multiset), immutable collections, a graph library, functional
types, an in-memory cache, and APIs/utilities for concurrency, I/O, hashing,
primitives, reflection, string processing, and much more!

Guava comes in two flavors.

*   The JRE flavor requires JDK 1.8 or higher.
*   If you need support for JDK 1.7 or Android, use the Android flavor. You can
    find the Android Guava source in the [`android` directory].

[`android` directory]: https://github.com/google/guava/tree/master/android

## 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 Java 7 or by any library that wants to be compatible with
either of those. These flavors are specified in the Maven version field as
either `27.1-jre` or `27.1-android`. For more about depending on
Guava, see [using Guava in your build].

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

```xml
<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>27.1-jre</version>
  <!-- or, for Android: -->
  <version>27.1-android</version>
</dependency>
```

To add a dependency using Gradle:

```gradle
dependencies {
  compile 'com.google.guava:guava:27.1-jre'
  // or, for Android:
  api 'com.google.guava:guava:27.1-android'
}
```

## Snapshots

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][guava-snapshot-api-docs]
- Snapshot API Diffs: [guava][guava-snapshot-api-diffs]

## Learn about Guava

- Our users' guide, [Guava Explained]
- [A nice collection](http://www.tfnico.com/presentations/google-guava) of other helpful links

## Links

- [GitHub project](https://github.com/google/guava)
- [Issue tracker: Report a defect or feature request](https://github.com/google/guava/issues/new)
- [StackOverflow: Ask "how-to" and "why-didn't-it-work" questions](https://stackoverflow.com/questions/ask?tags=guava+java)
- [guava-discuss: For open-ended questions and discussion](http://groups.google.com/group/guava-discuss)

## 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 at runtime:
`com.google.guava:failureaccess:1.0`

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 unit-test the libraries using only OpenJDK 1.8 on
Linux. Some features, especially in `com.google.common.io`, may not work
correctly in other environments. For the Android flavor, our unit tests run on
API level 15 (Ice Cream Sandwich).

[guava-snapshot-api-docs]: https://google.github.io/guava/releases/snapshot-jre/api/docs/
[guava-snapshot-api-diffs]: https://google.github.io/guava/releases/snapshot-jre/api/diffs/
[Guava Explained]: https://github.com/google/guava/wiki/Home
[Guava Beta Checker]: https://github.com/google/guava-beta-checker

<!-- References -->

[using Guava in your build]: https://github.com/google/guava/wiki/UseGuavaInYourBuild
[repackage]: https://github.com/google/guava/wiki/UseGuavaInYourBuild#what-if-i-want-to-use-beta-apis-from-a-library-that-people-use-as-a-dependency