Set JAVA_HOME on a Windows machine based on registry keys

set_java_home.bat

@echo off

setlocal

:: Check if JAVA_HOME is already defined
IF DEFINED JAVA_HOME (exit /b 0)

:: Get the JDK version from the registry
set KEY="HKLM\SOFTWARE\JavaSoft\Java Development Kit"
set VALUE=CurrentVersion
reg query %KEY% /v %VALUE% 2>nul || (
    echo JDK not installed
    exit /b 1
)
set JDK_VERSION=
for /f "tokens=2,*" %%a in ('reg query %KEY% /v %VALUE% ^| findstr %VALUE%') do (
    set JDK_VERSION=%%b
)

echo JDK VERSION: %JDK_VERSION%

:: Get the JDK path
set KEY="HKLM\SOFTWARE\JavaSoft\Java Development Kit\%JDK_VERSION%"
set VALUE=JavaHome
reg query %KEY% /v %VALUE% 2>nul || (
    echo JavaHome not defined
    exit /b 1
)

set JAVAHOME=
for /f "tokens=2,*" %%a in ('reg query %KEY% /v %VALUE% ^| findstr %VALUE%') do (
    set JAVAHOME=%%b
)

setx -m JAVA_HOME "%JAVAHOME%"

endlocal