To stop VS Code from auto-building all Java projects in a monorepo, disable Java auto-build, Gradle, and Maven auto-import in your workspace settings. Turn off automatic build configuration updates to prevent background project scanning. Use a .javaProjects file to limit Java language support to specific folders. Temporarily disable the Java extension when not needed to avoid unnecessary resource usage. Also, block extension suggestions for Java in .vscode/extensions.json to keep your workspace clean. These steps help you control Java behavior in large codebases and work efficiently without triggering builds for unrelated projects.