Swith java version in PowerShell. Saving the script and Appending '. "C:\Path\To\Your\Script\switch-java.ps1"' to "$PROFILE" file. For git-bash, put 'test -f ~/bin/switch-java.sh && . ~/bin/switch-java.sh' to '.bash_profile'

switch-java.sh

#!/usr/bin/env bash
# Git-Bash edition of Java version switcher
# Usage: source this file in your .bashrc, then call `switch-java <version>` or `sj <version>`
#   e.g.  sj 21

switch-java() {
    local version="$1"

    # Java installation paths (git-bash style)
    declare -A java_paths=(
        [8]="/c/Programs/dev/java/java"
        [11]="/c/Programs/dev/java/java11"
        [17]="/c/Programs/dev/java/java17"
        [21]="/c/Programs/dev/java/java21"
    )

    # Validate version
    if [[ -z "${java_paths[$version]+_}" ]]; then
        echo "Invalid Java version. Available versions: ${!java_paths[*]}"
        return 1
    fi

    local java_home="${java_paths[$version]}"

    # Remove all known Java paths from PATH
    local new_path="$PATH"
    for p in "${java_paths[@]}"; do
        # Remove both "<path>/bin" and "<path>" entries
        new_path=$(echo "$new_path" | tr ':' '\n' | grep -v -F "$p" | paste -sd ':' -)
    done

    # Prepend new Java bin path
    export PATH="${java_home}/bin:${new_path}"

    # Set JAVA_HOME (Windows-style for tools that expect it)
    local java_home_win
    java_home_win=$(cygpath -w "$java_home")
    export JAVA_HOME="$java_home_win"

    # Set CLASSPATH
    export CLASSPATH=".;${java_home_win}\\lib"

    echo "JAVA_HOME set to: $JAVA_HOME"
    echo "PATH updated to include: ${java_home}/bin"
    echo "CLASSPATH set to: $CLASSPATH"
    echo ""
    java -version
}

# Alias
alias sj='switch-java'

swith-java.ps1

function Switch-Java {
    param (
        [string]$Version
    )

    # The location of multi-version java
    $javaPaths = @{
        "8"  = "C:\Programs\dev\java\java"
        "11" = "C:\Programs\dev\java\java11"
        "17" = "C:\Programs\dev\java\java17"
    }

    # check input
    if (-not $javaPaths.ContainsKey($Version)) {
        Write-Host "Invalid Java version. Available versions: 8, 11, 17"
        return
    }

    # new java home
    $javaHome = $javaPaths[$Version]

    # set java home
    [System.Environment]::SetEnvironmentVariable("JAVA_HOME", $javaHome, [System.EnvironmentVariableTarget]::Process)

    # old path
    $currentPath = [System.Environment]::GetEnvironmentVariable("PATH", [System.EnvironmentVariableTarget]::Process)

    # remove outdated java path
    $newPath = ($currentPath -split ';' | Where-Object { 
        $javaPaths.Values -notcontains $_ -and $javaPaths.Values -notcontains ($_ -replace '\\bin$', '')
    }) -join ';'

    # new path
    $newPath = "$javaHome\bin;$newPath"

    [System.Environment]::SetEnvironmentVariable("PATH", $newPath, [System.EnvironmentVariableTarget]::Process)

    # classpath
    $classPath = ".;$($javaHome)\lib"
    [System.Environment]::SetEnvironmentVariable("CLASSPATH", $classPath, [System.EnvironmentVariableTarget]::Process)

    # print result JAVA_HOME\PATH\CLASSPATH
    Write-Host "JAVA_HOME set to: $javaHome"
    Write-Host "PATH updated to include: $javaHome\bin"
    Write-Host "CLASSPATH set to: $classPath"
	
    Write-Host ""

    # java now
    java -version
}

# alias
Set-Alias -Name sj -Value Switch-Java