Check installed Java version using terminal commands

Usage

java_check_version_cmd(java_home = NULL, quiet = FALSE, .use_cache = FALSE)

Arguments

java_home: Path to Java home directory. If NULL, the function uses the JAVA_HOME environment variable.
quiet: A logical value indicating whether to suppress messages. Can be TRUE or FALSE.
.use_cache: Logical. If TRUE, uses cached results for repeated calls with the same JAVA_HOME. If FALSE (default), forces a fresh check. Set to TRUE for performance in loops or repeated checks within the same session.

Value

A character vector of length 1 containing the major Java version, or FALSE if JAVA_HOME is not set or the Java executable cannot be found.

Performance

This function is memoised (cached) within the R session using the effective JAVA_HOME as cache key. First call for a given JAVA_HOME: ~37ms. Subsequent calls (with .use_cache = TRUE): <1ms. When you switch Java versions via use_java(), JAVA_HOME changes, creating a new cache entry. Cache is session-scoped.

Examples

# \donttest{
java_check_version_cmd()
#> JAVA_HOME:
#> /home/runner/.cache/R/rJavaEnv/installed/linux/x64/Corretto/native/17
#> Java path:
#> /home/runner/.cache/R/rJavaEnv/installed/linux/x64/Corretto/native/17/bin/java
#> Java version: "openjdk version \"17.0.17\" 2025-10-21 LTS OpenJDK Runtime
#> Environment Corretto-17.0.17.10.1 (build 17.0.17+10-LTS) OpenJDK 64-Bit Server
#> VM Corretto-17.0.17.10.1 (build 17.0.17+10-LTS, mixed mode, sharing)"
#> [1] "17"
# }