Improve javac version fetching.

crates/java/Cargo.toml

@@ -3,7 +3,7 @@
 
 [package]
 name = "java"
-version = "0.2.1"
+version = "0.2.2"
 edition.workspace = true
 license.workspace = true
 

crates/java/src/compiler.rs

@@ -1,9 +1,11 @@
+use std::fmt::Display;
 use std::path::{Path, PathBuf};
 
 use subprocess::Exec;
 use subprocess::Redirection;
 
 use crate::JAVA_BIN_COMPILER;
+use crate::JAVA_EXT_SOURCE;
 use crate::Result;
 
 #[derive(Debug, Default, Clone)]
@@ -48,26 +50,6 @@ pub struct Compiler {
 }
 
 impl Compiler {
-    /*
-    pub fn compile<P: AsRef<Path>>(self, path: P) -> Result<(Option<String>, Option<String>)> {
-        let mut cmd: Vec<String> = vec![JAVA_BIN_COMPILER.to_string()];
-
-        cmd.extend(
-            self.flags
-                .clone()
-                .into_iter()
-                .flat_map(|f| Into::<Vec<String>>::into(f)),
-        );
-        cmd.extend(
-            fs::expand_files(path)?
-                .into_iter()
-                .filter_map(|f| Some(f.to_str()?.to_string())),
-        );
-
-        Ok(io::run_process(cmd.as_slice())?)
-    }
-    */
-
     pub fn compile<P: AsRef<Path>>(self, path: P) -> Result<bool> {
         Ok(Exec::cmd(JAVA_BIN_COMPILER)
             .args(
@@ -76,7 +58,7 @@ impl Compiler {
                     .into_iter()
                     .flat_map(|f| Into::<Vec<String>>::into(f)),
             )
-            .arg(path.as_ref())
+            .arg(path.as_ref().with_extension(JAVA_EXT_SOURCE))
             .stdout(Redirection::Pipe)
             .detached()
             .start()?
@@ -89,6 +71,7 @@ impl Compiler {
 pub enum CompilerFlag {
     Classpath { path: PathBuf },
     Destination { path: PathBuf },
+    Version,
 }
 
 impl Into<Vec<String>> for CompilerFlag {
@@ -96,6 +79,18 @@ impl Into<Vec<String>> for CompilerFlag {
         match self {
             Self::Classpath { path } => vec!["-classpath".to_string(), path.display().to_string()],
             Self::Destination { path } => vec!["-d".to_string(), path.display().to_string()],
+            Self::Version => vec!["--version".to_string()],
+        }
+    }
+}
+
+// TODO: Clean this up a bit?
+impl Display for CompilerFlag {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Classpath { path } => write!(f, "-classpath {}", path.display()),
+            Self::Destination { path } => write!(f, "-d {}", path.display()),
+            Self::Version => write!(f, "--version"),
         }
     }
 }

crates/java/src/lib.rs

@@ -8,6 +8,8 @@ pub use error::{Error, Result};
 use runtime::VMFlag;
 use subprocess::Exec;
 
+use crate::compiler::CompilerFlag;
+
 pub const JAVA_BIN_VM: &str = "java";
 pub const JAVA_BIN_COMPILER: &str = "javac";
 
@@ -16,24 +18,22 @@ pub const JAVA_EXT_CLASS: &str = "class";
 
 pub const F_JAVA_VERSION: &str = ".java-version";
 
-/// Uses the java binary to parse its stdout for version information.
-///
-/// This is non-caching.
-pub fn get_javac_ver() -> Result<semver::Version> {
-    // TODO: Consider making this pull the version info from javac instead?
-
-    /*
-     * $ java --version
-     *      openjdk 21.0.9 2025-10-21
-     *      OpenJDK Runtime Environment (build 21.0.9+10)
-     *      OpenJDK 64-Bit Server VM (build 21.0.9+10, mixed mode, sharing)
-     */
+/// Uses the javac binary to get information about the install compiler.
+pub fn get_javac_version() -> Result<semver::Version> {
+    // Try to pull from javac first.
+    if let Ok(version) = semver::Version::from_str(
+        Exec::cmd(JAVA_BIN_COMPILER)
+            .arg(CompilerFlag::Version.to_string())
+            .capture()?
+            .stdout_str()
+            .replace("javac", "")
+            .trim(),
+    ) {
+        return Ok(version);
+    }
 
     Ok(semver::Version::from_str(
         get_java_version_info()?
-            .lines()
-            .nth(0)
-            .ok_or(Error::EmptyStdout)?
             .split_ascii_whitespace()
             .nth(1)
             .ok_or(Error::NthOutOfBounds)?,
@@ -42,8 +42,14 @@ pub fn get_javac_ver() -> Result<semver::Version> {
 
 /// Calls the java binary, returning the complete stdout version information.
 fn get_java_version_info() -> Result<String> {
+    /*
+     * $ java --version
+     *      openjdk 21.0.9 2025-10-21
+     *      OpenJDK Runtime Environment (build 21.0.9+10)
+     *      OpenJDK 64-Bit Server VM (build 21.0.9+10, mixed mode, sharing)
+     */
     Ok(Exec::cmd(JAVA_BIN_VM)
-        .arg(VMFlag::Version.to_string().as_str())
+        .arg(VMFlag::Version.to_string())
         .capture()?
         .stdout_str())
 }