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Java Version Manager (JVM)

A lightweight, high-performance, color-coded Windows Batch utility designed to dynamically discover, switch, download, update, and clean up Java Development Kit (JDK) environments without system bloat.

🚀 Features

  • Dynamic JDK Scanning: Automatically discovers installed JDK instances across multiple common system directories (C:\Program Files\Java, C:\Java, etc.) and builds a smart menu on the fly. No hardcoded versions.
  • Oracle JDK Auto-Downloader: Connects directly to official Oracle infrastructure via a transparent, isolated PowerShell instance to pull down and extract any modern major JDK version (17, 21, 25, 26, etc.).
  • Intelligent Update Checker: Queries official Oracle servers via high-speed HTTP HEAD requests to compare remote build dates against your local release file metadata. Automatically downloads, hot-swaps directories, and patches environment variables in-place if a newer build is found.
  • Dynamic Environment Switching: Atomically updates JAVA_HOME and your user/system PATH globally while cleanly updating the environment variables of your active terminal session without spawning double paths.
  • The "Phantom Path" Killer: Actively hunts down and scrubs rogue, hardcoded Oracle shortcuts (e.g., Common Files\Oracle\Java\javapath) that installers forcefully inject into the front of your PATH, ensuring JAVA_HOME is always respected.
  • Surgical Uninstaller: Safely terminates lingering background java.exe/javaw.exe processes, deletes the target directory, and scrubs any traces of that specific version from your registry and environment tables.
  • Optimized Elevation & Interface: Features an instantaneous, high-reliability net session Admin privilege check with zero UAC folder drift. Built using high-performance, instant-response key interception (choice.exe) and ANSI color coding.

📋 Prerequisites

  • OS: Windows 10 or Windows 11
  • Privileges: Administrator rights are required to modify system-level environment variables and registry strings. (The script will automatically request elevation via a optimized UAC pop-up if launched unprivileged).

🛠️ Usage

  1. Copy the script code into a file named jvm.bat or manager.bat.
  2. Right-click the file and select Run as administrator (or simply launch it normally and accept the UAC prompt).
  3. Interact with the menu using your number keys:
    • Numbers 1 through X: Instantly sets your active JAVA_HOME to that directory.
    • Latest JDK Shortcut: Quickly fast-forwards your system configuration to the highest version number found on your machine.
    • Check for Updates: Bulk-scans all installed JDKs (or an individual version) against Oracle's servers to automatically fetch and install the latest security patches and minor builds.
    • Download/Install: Installs a brand new major version directly from Oracle to C:\Program Files\Java.
    • Uninstall: Safely and completely removes a JDK environment and scrubs lingering system paths.

🎨 Interface Guide

The utility uses native ANSI terminal color formatting to protect system stability:

  • 🔹 Cyan [ ACTION ] / [ INFO ] — Indicates system operations, network lookups, and diagnostic information.
  • 🔸 Yellow [ WARNING ] / [ UPDATE ] — Points out non-critical issues, available patches, or destructive prompts.
  • 🔺 Red [ ERROR ] — Warns of network failures, blocked file permissions, or locked folders.
  • 🔹 Green [ACTIVE] / [ OK ] — Highlights the JDK entry currently actively powering your terminal environment, or signifies a successful operation.

🛡️ Safety Defaults

To prevent catastrophic accidental deletions on local filesystems, all critical prompts obey standard developer conventions:

  • The uninstaller and update prompts use a strict (y/N) validation.
  • Pressing Enter or typing anything other than an explicit Y/y acts as an immediate safe abort.
  • Custom loops trap premature Ctrl+C commands gracefully without throwing broken system syntax messages or dropping terminal sessions.

📜 Version History

  • v0.2.0 (Latest): Added intelligent update checker (via HTTP HEAD requests), "Update All" bulk-patching, and automated directory hot-swapping.
  • v0.1.1: Patched PATH variable corruption bugs and improved delayed-expansion safety protocols during active session switching.
  • v0.1.0: Initial Release (Dynamic scanning, Oracle downloader, Phantom Path cleaner, and surgical uninstaller).

📄 License

This tool is provided as open-source infrastructure under the MIT License. Oracle JDK downloads are subject to the Oracle No-Fee Terms and Conditions (NFTC).