@echo off
: in this case:currentdir: ISCS6000_HOME
start /w jdk.exe /s ADDLOCAL="ToolsFeature,SourceFeature" INSTALLDIR=C:\Java\jdk
reg query "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v path | findstr "%%JAVA_HOME%%" && goto :case1 || goto :case2
pause
goto :eof

:case1
echo "case1"
setx /M JAVA_HOME "C:\Java\jdk\bin"
goto :eof

:case2
echo "case2"
for /f "tokens=2*" %%I in (
    'reg query "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v path'
) do set "HKLMpath=%%J"

setlocal enabledelayedexpansion
setx /M JAVA_HOME "C:\Java\jdk\bin"
wmic ENVIRONMENT where "name='path' and username='<SYSTEM>'" set VariableValue="!HKLMpath!;%%JAVA_HOME%%"
goto :eof