setup-java/README.md

# setup-java

<p align="left">
  <a href="https://github.com/actions/setup-java"><img alt="GitHub Actions status" src="https://github.com/actions/setup-java/workflows/Main%20workflow/badge.svg"></a>
</p>

This action provides the following functionality for GitHub Actions runners:
- Downloading and setting up a requested version of Java. See [Usage](#Usage) for a list of supported distributions
- Extracting and caching custom version of Java from a local file
- Configuring runner for publishing using Apache Maven
- Configuring runner for publishing using Gradle
- Configuring runner for using GPG private key
- Registering problem matchers for error output

## V2 vs V1
- V2 supports custom distributions and provides support for Zulu OpenJDK and Adopt OpenJDK out of the box. V1 supports only Zulu OpenJDK
- V2 requires you to specify distribution along with the version. V1 defaults to Zulu OpenJDK, only version input is required. Follow [the migration guide](docs/switching-to-v2.md) to switch from V1 to V2

## Usage
Inputs `java-version` and `distribution` are mandatory. See [Supported distributions](../README.md#Supported-distributions) section for a list of available options.

### Basic
**Adopt OpenJDK**
```yaml
steps:
- uses: actions/checkout@v2
- uses: actions/setup-java@v2-preview
  with:
    distribution: 'adopt' # See 'Supported distributions' for available options
    java-version: '11'
- run: java -cp java HelloWorldApp
```

**Zulu OpenJDK**
```yaml
steps:
- uses: actions/checkout@v2
- uses: actions/setup-java@v2-preview
  with:
    distribution: 'zulu' # See 'Supported distributions' for available options
    java-version: '11'
- run: java -cp java HelloWorldApp
```

#### Supported version syntax
The `java-version` input supports an exact version or a version range using [SemVer](https://semver.org/) notation:
- major versions: `8`, `11`, `15`
- more specific versions: `11.0`, `11.0.4`, `8.0.232`, `8.0.282+8`
- early access (EA) versions: `15-ea`, `15.0.0-ea`, `15.0.0-ea.2`, `15.0.0+2-ea`

#### Supported distributions
Currently, the following distributions are supported:
| Keyword | Distribution | Official site | License |
|-|-|-|-|
| `zulu` | Zulu OpenJDK | [Link](https://www.azul.com/downloads/zulu-community/?package=jdk) | [Link](https://www.azul.com/products/zulu-and-zulu-enterprise/zulu-terms-of-use/) |
| `adopt` | Adopt OpenJDK | [Link](https://adoptopenjdk.net/) | [Link](https://adoptopenjdk.net/about.html)

**NOTE:** The different distributors can provide discrepant list of available versions / supported configurations. Please refer to the official documentation to see the list of supported versions.

### Check latest
In the basic examples above, the `check-latest` flag defaults to `false`. When set to `false`, the action tries to first resolve a version of Java from the local tool cache on the runner. If unable to find a specific version in the cache, the action will download a version of Java. Use the default or set `check-latest` to `false` if you prefer a faster more consistent setup experience that prioritizes trying to use the cached versions at the expense of newer versions sometimes being available for download.

If `check-latest` is set to `true`, the action first checks if the cached version is the latest one. If the locally cached version is not the most up-to-date, the latest version of Java will be downloaded. Set `check-latest` to `true` if you want the most up-to-date version of Java to always be used. Setting `check-latest` to `true` has performance implications as downloading versions of Java is slower than using cached versions.

For Java distributions that are not cached on Hosted images, `check-latest` always behaves as `true` and downloads Java on-flight. Check out [Hosted Tool Cache](docs/advanced-usage.md#Hosted-Tool-Cache) for more details about pre-cached Java versions.  


```yaml
steps:
- uses: actions/checkout@v2
- uses: actions/setup-java@v2-preview
  with:
    distribution: 'adopt'
    java-version: '11'
    check-latest: true
- run: java -cp java HelloWorldApp
```

### Testing against different Java versions
```yaml
jobs:
  build:
    runs-on: ubuntu-20.04
    strategy:
      matrix:
        java: [ '8', '11', '13', '15' ]
    name: Java ${{ matrix.Java }} sample
    steps:
      - uses: actions/checkout@v2
      - name: Setup java
        uses: actions/setup-java@v2-preview
        with:
          distribution: '<distribution>'
          java-version: ${{ matrix.java }}
      - run: java -cp java HelloWorldApp
```

### Advanced
- [Selecting a Java distribution](docs/advanced-usage.md#Selecting-a-Java-distribution)
  - [Adopt](docs/advanced-usage.md#Adopt)
  - [Zulu](docs/advanced-usage.md#Zulu)
- [Installing custom Java package type](docs/advanced-usage.md#Installing-custom-Java-package-type)
- [Installing custom Java architecture](docs/advanced-usage.md#Installing-custom-Java-architecture)
- [Installing custom Java distribution from local file](docs/advanced-usage.md#Installing-Java-from-local-file)
- [Testing against different Java distributions](docs/advanced-usage.md#Testing-against-different-Java-distributions)
- [Testing against different platforms](docs/advanced-usage.md#Testing-against-different-platforms)
- [Publishing using Apache Maven](docs/advanced-usage.md#Publishing-using-Apache-Maven)
- [Publishing using Gradle](docs/advanced-usage.md#Publishing-using-Gradle)
- [Hosted Tool Cache](docs/advanced-usage.md#Hosted-Tool-Cache)

## License

The scripts and documentation in this project are released under the [MIT License](LICENSE)

## Contributions

Contributions are welcome!  See [Contributor's Guide](docs/contributors.md)