Java Index for VS Code

Fast, lightweight Java navigation from java-index: go to definition, exact references, hover, implementations, type and call hierarchies, and Spring Boot / Quarkus config keys linked to the Java that reads them.

Why it's fast

A traditional Java language server such as jdtls imports your build and compiles the whole project. java-index doesn't compile at all. It parses sources with Google's turbine header compiler into compact declaration summaries, resolves method bodies only when you ask about them, and serves every window, agent session and git worktree of a repository from one shared background daemon. It never writes into your project, so it never fights your build over target/.

Measured on spring-petclinic against jdtls with VS Code's default settings (benchmark, medians):

	java-index	jdtls
Ready to answer, cold / warm start	1.5 s / 0.4 s	2.7 s / 1.8 s
Memory, one window	250 MB	1.8 GB
CPU time to open one window, cold	7 s	54 s
Find references on a common method	2 ms	385 ms
8 worktrees open at once: memory	416 MB	12.8 GB
8 worktrees open at once: CPU	11 s	428 s

That benchmark is one small Maven project. jdtls is heavier partly because it does more: java-index is built for reading Java, e.g. reviewing what your agents wrote, so there are no compiler errors, completion or refactorings, and Lombok-generated members are not seen. See java-index vs jdtls for the full trade-off.

Spring Boot and Quarkus configuration

Keys in application*.properties, application*.yml, bootstrap*.yml and microprofile-config.properties are linked both ways with the Java that uses them: @Value, @ConfigurationProperties, @ConfigProperty, @ConfigMapping and getProperty("…").

Go to definition on a key in Java jumps to where it is set, in every profile.
Find references on a key in a config file lists the code that reads it.
Hover shows the value per profile and, for library keys such as server.port, the documented type, default and description.

Spring's relaxed binding is honoured.

Server

The extension runs, in order:

javaIndex.server.path (with javaIndex.server.arguments), if set;
jindex from the PATH, e.g. installed with Homebrew;
otherwise the java-index release matching this extension's version, downloaded once from GitHub releases and checked against its SHA256SUMS: the native relay on Apple Silicon Macs and Linux (x64, arm64), the jar elsewhere.

The daemon runs on Java 21 or later: javaIndex.java.home, else $JINDEX_JAVA, $JAVA_HOME, java from the PATH, or the JDK in java.jdt.ls.java.home.

With the Red Hat Java extension

VS Code highlights Java on its own, so this extension works alone. If the Red Hat Java extension is also enabled, both servers answer and you see results twice; disable it for workspaces you review with java-index.

Settings

Setting	Default
`javaIndex.server.path`		command that runs the server
`javaIndex.server.arguments`	`[]`	its arguments, e.g. `["-jar", "/path/to/java-index.jar"]`
`javaIndex.java.home`		JDK 21+ for the daemon
`javaIndex.classpath`	build tool	jars or jar directories, instead of asking Maven or Gradle
`javaIndex.inlayHints.parameterNames`	`"literals"`	`"all"` or `"none"`
`javaIndex.inlayHints.types`	`true`	`var`, lambda parameter and chain type hints
`javaIndex.deprecations`	`true`	mark uses of deprecated APIs
`javaIndex.trace.server`	`"off"`	log LSP messages to the Java Index output

Commands: Java Index: Restart Server and Java Index: Show Output.

Build

npm install
npm run package    # java-index-<version>.vsix
code --install-extension java-index-<version>.vsix

Java Index

Gobinath