Java Version Switcher

A quick way to change between java versions in windows cmd

Installation:

Put jvs.exe in a folder, and add that folder to your system PATH environnement variable. Make sure jvs.exe is in a folder where it has read/write permissions.

Config:

{
    "17": "C:/Program Files/Zulu/zulu-17",
    "8": "C:/Program Files/Zulu/zulu-8",
    "install": {
        "zulu17": "https://cdn.azul.com/zulu/bin/zulu17.44.53-ca-jdk17.0.8.1-win_x64.zip",
        "zulu20": "https://cdn.azul.com/zulu/bin/zulu20.32.11-ca-jdk20.0.2-win_x64.zip",
        "zulu8": "https://cdn.azul.com/zulu/bin/zulu8.72.0.17-ca-jdk8.0.382-win_x64.zip"
    }
}

The config jvs.json needs to be in the same folder as jvs.exe.

In this example config, the command jvs 17 will delete existing java dirs in the PATH env variable, and add the directory C:/Program Files/Zulu/zulu-17/bin to PATH.
It will also set JAVA_HOME to C:/Program Files/Zulu/zulu-17.

The command jvs install zulu17 will download the zip file at https://cdn.azul.com/zulu/bin/zulu17.44.53-ca-jdk17.0.8.1-win_x64.zip and extract it to a folder zulu17 in the same place as jvs.exe.
It will then add that folder to jvs.json so that you can jvs zulu17.

Usage:

jvs <javaVersion>

jvs install <javaVersion>

Info:

This does not change the system wide PATH env variable, it calls _putenv in the parent process (so cmd.exe), so that only that process java path will be changed. It uses VirtualAllocEx, WriteProcessMemory and CreateRemoteThread in order to achieve that.

External Libraries used:

• nlohmann json: https://github.com/nlohmann/json (for the json config jvs.json)
• curl: https://github.com/curl/curl (to download jdk zip)
• miniz: https://github.com/richgel999/miniz (to extract downloaded jdk zip)
• indicators: https://github.com/p-ranav/indicators (for the progress bar)

Why a c++ program instead of a simple batch/powershell script ?

Because c++ is fun, and it allows to have a cool json config file, as well as the ability to remove existing java paths to avoid conflicts. Overall it's fast, and it will allow more features in the future.