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rJavaEnv: Java Environments for R Projects

The goal of rJavaEnv is to manage multiple Java JDKs in R projects by automating the process of downloading, installing, and configuring Java environments on a per-project basis. This package is inspired by the renv package for managing R environments in R projects.

You can request a specific Java Development Kit (JDK) in your project, and rJavaEnv will download and install the requested Java environment in a project-specific directory and set the PATH and JAVA_HOME for when you are using this project. Therefore, you can have different Java versions for different projects without contaminating your system with different Java versions.

WARNING This package is in the early stages of development and is not yet ready for production use. Please test it thoroughly before using it in your projects.

Install

You can install the development version of rJavaEnv from GitHub:

if (!requireNamespace("remotes", quietly = TRUE)) {
  install.packages("remotes")
}

remotes::install_github("e-kotov/rJavaEnv")

Simple Example 

rJavaEnv::java_quick_install(version = 21)

This will:

  • download Java 21 distribution compatible with the current operating system and processor architecture into a local cache folder;

  • extract the downloaded Java distribution into another cache folder;

  • create a symbolic link (for macOS and Linux) or junction (for Windows, if that fails, just copies the files) rjavaenv/platform/processor_architecture/java_version in the current directory/project to point to the cached installation;

  • set the current session’s JAVA_HOME and PATH environment variables to point to the installed (symlinked) Java distribution;

  • add code to .Rprofile file in the current directory/project to set JAVA_HOME and PATH environment variables when the project is opened in RStudio.

After that, you can even remove rJavaEnv completely, as the Java environment will be set up in the project directory with the base R code that does not rely on rJavaEnv.

Functions Overview

The package has several core functions:

  1. java_quick_install()
    • Downloads, installs, and sets Java environment in the current working/project directory, all in one line of code.
  2. java_check_version_cmd()
    • Checks the installed Java version using terminal commands. For packages like opentripplanner, that performs Java calls using command line.
  3. java_version_check_rjava()
    • Checks the installed Java version using rJava in a separate R session. For rJava-dependent packages such as r5r.
  4. java_download()
    • Downloads a specified version and distribution of Java.
  5. java_install()
    • Installs a Java distribution file into current (or user-specified) project directory.
  6. java_env_set()
    • Sets the JAVA_HOME and PATH environment variables to a given path in current R session and/or in the .Rprofile file in the project directory.
  7. java_env_unset()
    • Remove the JAVA_HOME and PATH environment variables from the .Rpofile file in the project directory (but not in the current R session, please restart the session so that R picks up the system Java).
  8. java_list()
    • Lists all or some Java versions linked in the current project (or cached distributions or installations).
  9. java_clear()
    • Removes all or some Java versions linked in the current project (or cached distributions or installations).

See more details on all the functions in the Reference.

For detailed usage, see the Quick Start Vignette (work in progress).

Limitations

Currently, rJavaEnv only supports major Java versions such as 8, 11, 17, 21, 22. The download and install functions ignore the minor version of the Java distribution and just downloads the latest stable subversion of the specified major version. This is done to simplify the process and avoid the need to update the package every time a new minor version of Java is released. For most users this should be sufficient, but this is substandard for full reproducibility.

The main limitation is that if you want to switch to another Java environment, you will most likely have to restart the current R session and set the JAVA_HOME and PATH environment variables to the desired Java environment using rJavaEnv::java_env_set(). This cannot be done dynamically within the same R session due to the way Java is initialized in R, particularly with the rJava-dependent packages such as r5r. With packages like opentripplanner, that performs Java calls using command line, you can switch Java environments dynamically within the same R session as much as you want.

Therefore, if you need to use R packages that depend on different Java versions within the same project, you will have to create separate R scripts for each Java environment and run them in separate R sessions. One effective way of doing this is to use the callr package to run R scripts in separate R sessions. Another option is to use the targets package to manage the whole project workflow, which, as a side effect, will lead to all R scripts being run in separate R sessions. To use rJavaEnv with targets, you will need to download and install several Java environments using rJavaEnv::java_download() and rJavaEnv::java_install() and set the relevant path with rJavaEnv::java_env_set() at the beginning of each function that requires a certain Java version.

Future work

The future work includes:

  • Add support for more Java distributions and versions

  • Take care of R CMD javareconf

  • Possibly add support for specifying Java version beyond the major version

  • Possibly allow downloading several Java distributions in one function call, e.g. different major versions of the same ‘flavour’ or different ‘flavours’ of the same major version

  • Possibly add automation to get the Java that is required by specific Java-dependent R packages

I am open to suggestions and contributions, welcome to issues and pull requests.

Acknowledgements

I thank rOpenSci for the Dev Guide, as well as Hadley Wickham and Jennifer Bryan for the R Packages book.

Package hex sticker logo is partially generated by DALL-E by OpenAI. The logo also contains the original R logo.

Citation

To cite package ‘rJavaEnv’ in publications use:

Kotov E (2024). rJavaEnv: Java Environments for R Projects. doi:10.5281/zenodo.11403010 https://doi.org/10.5281/zenodo.11403010, https://github.com/e-kotov/rJavaEnv.

BibTeX:

@Manual{rjavaenv,
  title = {rJavaEnv: Java Environments for R Projects},
  author = {Egor Kotov},
  year = {2024},
  url = {https://github.com/e-kotov/rJavaEnv},
  doi = {10.5281/zenodo.11403010},
}