.java-version file support

[pavolzbell]

Hello, I think it would be nice to set java-version default value by reading .java-version file if it exists, what do you think?

This change is inspired by ruby-setup action which already does the same with .ruby-version file. The use of .java-vesion file is popularized by jenv.

[Fleshgrinder]

I'd like to add here that it would be awesome if the content of that file is used by default if present. Basically making the java-version optional. This would lead to zero configuration. 🤩

[Fleshgrinder]

I found a way to add support for .java-version files that can act as an escape hatch for everyone who wants this functionality today:

    - name: Export .java-version
      run: |
        java_version=11
        if [[ -f .java-version ]]; then
          java_version=$(head -1 .java-version)
        else
          echo "::error file=.java-version::Missing .java-version file, falling back to default Java version: $java_version"
        fi
        echo "JAVA_VERSION=$java_version" >>"$GITHUB_ENV"
    - uses: actions/setup-java@v2
      with:
        distribution: temurin
        java-version: ${{ env.JAVA_VERSION }}

This can of course be simplified if you use it in a repository where the .java-version file is always guaranteed to exist:

    - name: Export .java-version
      run: echo "JAVA_VERSION=$(head -1 .java-version)" >>"$GITHUB_ENV"
    - uses: actions/setup-java@v2
      with:
        distribution: temurin
        java-version: ${{ env.JAVA_VERSION }}

[Fleshgrinder]

I got tired and created a wrapping action: https://github.com/Fleshgrinder/setup-java

[dmitry-shibanov]

Hello everyone. Sorry for the late response. We released a version of setup-java to pass a .java-version file through the java-version-file input .

[IvanZosimov]

I'm closing this feature request as completed. Related release: https://github.com/actions/setup-java/releases/tag/v3.9.0