Discover from a batch file where is Java installed?

Question

I want to set the JAVA_HOME variable from a batch script

Answer 1

This snippet will search the current PATH for java.exe, and print out where it was found:

for /f %%j in ("java.exe") do @echo.%%~dp$PATH:j

On my system this gives me

C:\WINDOWS\system32\

Using this you can set JAVA_HOME as follows:

@echo off

for /f %%j in ("java.exe") do (
    set JAVA_HOME=%%~dp$PATH:j
)

if %JAVA_HOME%.==. (
    @echo java.exe not found
) else (
    @echo JAVA_HOME = %JAVA_HOME%
)

Answer 2

If JAVA_HOME isn't already set, and you want to set it, then you probably need to do something like

dir java.exe /B /S

which will give you a list of all directories containing the file java.exe. From there you can pipe that output to another command that parses the results and selects one of those directories, then uses it to set the JAVA_HOME variable.