How do I tell Gradle to use specific JDK version?

Question

I can't figure out to get this working.

Scenario:

• I have an application built with gradle
• The application uses JavaFX

What I want

• Use a variable (defined per developer machine) which points to an installation of a JDK which will be used for building the whole application / tests / ...

I thought about having the gradle.properties file, defining the variable. Something like

JAVA_HOME_FOR_MY_PROJECT=<path to my desired JDK>

What I don't want

• point JAVA_HOME to the desired JDK

I could live with many suggestions:

• a solution that defines a system environment variable which I'm able to check in my build.gradle script
• a variable defined in gradle.properties
• overriding the JAVA_HOME variable only for the build context (something like use JAVA_HOME=<my special JDK path defined somewhere else defined>)
• something else I didn't think about

Question:

• How to wire a variable (how ever defined, as variable in the gradle.properties, system environment variable, ...) to the build process?

I have more than one JDK7 available and need to point to a special version (minimum JDK_u version).

Any answer is appreciated and I'm thankful for every hint to the right direction.

Answer 1

If you are executing using gradle wrapper, you can run the command with JDK path like following

./gradlew -Dorg.gradle.java.home=/jdk_path_directory

Answer 2

Two ways

1. In gradle.properties in the .gradle directory in your HOME_DIRECTORY set org.gradle.java.home=/path_to_jdk_directory

2. In your build.gradle

   compileJava.options.fork = true
   compileJava.options.forkOptions.executable = /path_to_javac
   

Answer 3

There is one more option to follow. In your gradle tasks, you can set your desired jdk path. (I know this is a while since the question was posted. This answer can help someone.)

Right click on the deploy or any other task and select "Open Gradle Run Configuration..."

Then navigate to "Java Home" and paste your desired java path.

Please note that, bin will be added by the gradle task itself. So don't add the "bin" to the path.

Answer 4

I added this line in my GRADLE_HOME/bin/gradle file - export JAVA_HOME=/path/to/java/version

Answer 5

To people ending up here when searching for the Gradle equivalent of the Maven property maven.compiler.source (or <source>1.8</source>):

In build.gradle you can achieve this with

apply plugin: 'java'
sourceCompatibility = 1.8
targetCompatibility = 1.8

See the Gradle documentation on this.

Answer 6

I am using Gradle 4.2 . Default JDK is Java 9. In early day of Java 9, Gradle 4.2 run on JDK 8 correctly (not JDK 9).

I set JDK manually like this, in file %GRADLE_HOME%\bin\gradle.bat:

@if "%DEBUG%" == "" @echo off
@rem ##########################################################################
@rem
@rem  Gradle startup script for Windows
@rem
@rem ##########################################################################

@rem Set local scope for the variables with windows NT shell
if "%OS%"=="Windows_NT" setlocal

set DIRNAME=%~dp0
if "%DIRNAME%" == "" set DIRNAME=.
set APP_BASE_NAME=%~n0
set APP_HOME=%DIRNAME%..

@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
set DEFAULT_JVM_OPTS=

@rem Find java.exe
if defined JAVA_HOME goto findJavaFromJavaHome

@rem VyDN-start.
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_144\
@rem VyDN-end.

set JAVA_EXE=java.exe
%JAVA_EXE% -version >NUL 2>&1
if "%ERRORLEVEL%" == "0" goto init

echo.
echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
echo.
echo Please set the JAVA_HOME variable in your environment to match the
echo location of your Java installation.

goto fail

:findJavaFromJavaHome
set JAVA_HOME=%JAVA_HOME:"=%


@rem VyDN-start.
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_144\
@rem VyDN-end.


set JAVA_EXE=%JAVA_HOME%/bin/java.exe

if exist "%JAVA_EXE%" goto init

echo.
echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
echo.
echo Please set the JAVA_HOME variable in your environment to match the
echo location of your Java installation.

goto fail

:init
@rem Get command-line arguments, handling Windows variants

if not "%OS%" == "Windows_NT" goto win9xME_args

:win9xME_args
@rem Slurp the command line arguments.
set CMD_LINE_ARGS=
set _SKIP=2

:win9xME_args_slurp
if "x%~1" == "x" goto execute

set CMD_LINE_ARGS=%*

:execute
@rem Setup the command line

set CLASSPATH=%APP_HOME%\lib\gradle-launcher-4.2.jar

@rem Execute Gradle
"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.launcher.GradleMain %CMD_LINE_ARGS%

:end
@rem End local scope for the variables with windows NT shell
if "%ERRORLEVEL%"=="0" goto mainEnd

:fail
rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
rem the _cmd.exe /c_ return code!
if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
exit /b 1

:mainEnd
if "%OS%"=="Windows_NT" endlocal

:omega