Set system environment variables for Java development in Windows.

java.ps1

<#
.SYNOPSIS
    .
.DESCRIPTION
    Set system environment variables for JAVA development.
.PARAMETER Arch (a)
    The JDK architecture. e.g., x64, x86 (32 bit)
.PARAMETER Name (n)
    The name of the folder where the JDK is installed, e.g., jdk1.8.0_172
.EXAMPLE
    C:\PS>
    ./java.ps1 -a x64 -n jdk1.8.0_172
.NOTES
    Author: Jim Frenette
    Date:   June 30, 2018
#>

# since we're setting machine level environment variables using .NET framework integration
# an elevated PowerShell prompt as the Administrator Role is required
function CheckForElevatedSession
{
    # 1. find out who the user is
    $WindowsIdentity = [System.Security.Principal.Windowsidentity]::GetCurrent()
    # 2. instantiate a new Windows Security Principal object using the $WindowsIdentity as its argument.
    #    this object is necessary because it exposes the IsInRole method.
    $Principal = New-Object System.Security.Principal.WindowsPrincipal($WindowsIdentity)

    $AdminRole = [System.Security.Principal.WindowsBuiltInRole]::Administrator

    if ($Principal.IsInRole($AdminRole)) {
        Write-Host -ForegroundColor Green "Elevated PowerShell session detected. Continuing."
    } else {
        Write-Host -ForegroundColor Red "This script must be run in an elevated PowerShell window. Please launch an elevated session and try again."
        break
    }
}

function SetJavaEnv
{
    # Param needs to be at the top if not in a function
    Param(

        [parameter(mandatory=$true,
        HelpMessage="Enter the architecture, e.g., x64 or x86 (32 bit)")]
        [alias("a")]
        [String]
        $Arch,

        [parameter(mandatory=$true,
        HelpMessage="Enter the name of the folder where the JDK is installed, e.g., jdk1.8.0_172 or jdk-10.0.1")]
        [alias("n")]
        [String]
        $Name

    ) #end param

    # set javapath var
    switch ($Arch.ToLower())
    {
        "x64" {
            $JavaPath = $Env:ProgramFiles + "\Java"
            break
        }
        "x86" {
            $JavaPath = ${Env:ProgramFiles(x86)} + "\Java"
            break
        }
        default {
            Write-Host -ForegroundColor Red "invalid architecture parameter:" $Arch
            Write-Host -ForegroundColor Red "must be either x64 or x86"
            exit
        }
    }

    if ( Test-Path -Path $JavaPath\$Name ) {

        $Confirm = Read-Host "Set JAVA_HOME = "$JavaPath\$Name "? [y/n]"

        if ($Confirm.ToLower() -eq 'n') { exit }

        # set machine level environment variable using .NET framework integration
        [Environment]::SetEnvironmentVariable("JAVA_HOME", $JavaPath + "\" + $Name, "Machine")

        $JavaBin = $JavaPath + "\" + $Name + "\bin"

        $Confirm = Read-Host "ADD" $JavaBin "TO PATH  ? [y/n]"

        if ($Confirm.ToLower() -eq 'n') { exit }

        # get the current PATH from the environment keys in the registry
        $ExistingPath = [System.Environment]::GetEnvironmentVariable("path")

        # update the path
        $PathArray = $ExistingPath -split ';'
        if ($PathArray -notcontains $JavaBin) {
            $PathArray = $PathArray + $JavaBin | Where-Object { $_ }
            $Path = $PathArray -join ';'
        }

        # update the path
        # $Path = $ExistingPath + ";" + $JavaBin
        [System.Environment]::SetEnvironmentVariable("path", $Path, "Machine")

    } else {
        Write-Host -ForegroundColor Red "JDK Path:" $JAVAPATH\$name " does not exist"
        exit
    }

}

CheckForElevatedSession
SetJavaEnv