How to set JAVA_HOME to custom path in BATCH-CodePudding

How to set custom JAVA_HOME if JAVA_HOME does not exist yet.

if "%JAVA_HOME%" == "" (
    echo Setting JAVA_HOME
    set jdk=%~dp0openjdk-10.5.10
    echo %jdk%
    SETX /M JAVA_HOME "%jdk%"
    SETX /m PATH "%path%;%jdk%"
)

CodePudding user response：

I would not use the code block at all, in fact, I would not do this at all, I am just posting a much simple solution to your problem:

if defined JAVA_HOME goto :EOF
set "jdk=%~dp0openjdk-10.5.10"
echo %jdk%

This will simply fall through the if defined statement, should the variable not exist.

This is still a bad idea as this assumes that the java directories exist on the drive and in the path of the batch-file. I am more concerned with the earlier question where you wanted to mach java versions, which tells me you are unsure of what is/is not installed thus far.

I will not use setx here as it WILL destroy your path variable. Please also make a copy of your path variables before you attempt to use setx on it (though still not recommended.)

CodePudding user response：

try like this:

setlocal enableDelayedExpansion
if "%JAVA_HOME%" == "" (
    echo Setting JAVA_HOME
    set "jdk=%~dp0openjdk-10.5.10"
    echo !jdk!
    SETX /M JAVA_HOME "!jdk!"
    SETX PATH "!PATH!;!jdk!"
)

more about the delayed expansion -> https://ss64.com/nt/delayedexpansion.html