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JEnv for Windows Version 2 is here.

A complete rewrite of V.1

Change your current Java version with 3 words

  • JEnv allows you to change your current JDK Version.
  • This is helpful for testing or if you have projects requiring different versions of java
  • For example you can build a gradle project which requires java8 without changing your environment variables and then switch back to work with java15
  • It's written in cmd and powershell so it can change the environment variables and can run on any Windows-10+.

I hope you enjoy it. Please give me a star if you like my work. Thank you!

Video Demo:

jenv

Installation

  1. Clone this repository
  2. Add it to the path
  3. Run jenv once so the script can do the rest
  4. If your using cmd you need to call the batch file. If you use powershell you should call /src/jenv.ps1
  5. Some reported problems putting JEnv into their C:/Programs folder due to required admin rights
  6. I hope I could help you. Else open an issue

Warning:

Sometimes its necessary to call jenv when entering a new directory with a local jenv specified. This will set your JAVA_HOME for the current shell and ensures that tools like maven work properly

Usage (Note: local overwrites change. use overwrites local)

  1. Add a new Java environment (requires absolute path)
    jenv add <name> <path>
    Example: jenv add jdk15 D:\Programme\Java\jdk-15.0.1

  2. Change your java version for the current session
    jenv use <name>
    Example: jenv use jdk15
    Environment var for scripting:
    ---PowerShell: $ENV:JENVUSE="jdk17"
    ---CMD/BATCH: set "JENVUSE=jdk17"

  3. Clear the java version for the current session
    jenv use remove
    Example: jenv use remove
    Environment var for scripting:
    ---PowerShell: $ENV:JENVUSE=$null
    ---CMD/BATCH: set "JENVUSE="

  4. Change your java version globally
    jenv change <name>
    Example: jenv change jdk15

  5. Always use this java version in this folder
    jenv local <name>
    Example: jenv local jdk15

  6. Clear the java version for this folder
    jenv local remove
    Example: jenv local remove

  7. List all your Java environments
    jenv list
    Example: jenv list

  8. Remove an existing JDK from the JEnv list
    jenv remove <name>
    Example: jenv remove jdk15

  9. Enable the use of javac, javaw or other executables sitting in the java directory
    jenv link <Executable name>
    Example: jenv link javac

  10. Uninstall jenv and automatically restore a Java version of your choice
    jenv uninstall <name>
    Example: jenv uninstall jdk17

  11. Automatically search for java versions to be added
    jenv autoscan [--yes|-y] ?<path>?
    Example: jenv autoscan "C:\Program Files\Java"
    Example: jenv autoscan // Will search entire system Example: jenv autoscan -y "C:\Program Files\Java" // Will accept defaults

How does this work?

This script creates a java.bat file that calls the java.exe with the correct version When the ps script changes env vars they get exported to tmp files and applied by the batch file An additional parameter to the PowerShell script was added. "--output" alias "-o" will create the tmp files for the batch. See images below

SystemEnvironmentVariablesHirachyShell

SystemEnvironmentVariablesHirachyPowerShell PNG

Contributing

If you want to contribute feel free to do so. This is a great repository for beginners as the amount of code is not huge and you can understand how it works pretty easily.
For running tests I suggest you to use the latest version of powershell (pwsh.exe):
https://docs.microsoft.com/en-us/powershell/scripting/install/installing-powershell-on-windows?view=powershell-7.2
Be careful you have to run it as pwsh and not as powershell
Then you have to install Pester. This is only for tests: Install-Module -Name Pester -Force -SkipPublisherCheck
You could use your already installed powershell as well. However it has an old Pester Module already installed which you can not use and I could not figure out how it can be updated: pester/Pester#1201
Navigate into the test folder and run the test.ps1 file. It will backup your env vars and your jenv config while testing and automatically restore them later. But you should always let the tests finish else your vars and config wont be restored