How to enforce a java compiler version with gradle?
I use the following:
task checkJavaVersion << {
if (!JavaVersion.current().isJava6()) {
String message = "ERROR: Java 1.6 required but " +
JavaVersion.current() +
" found. Change your JAVA_HOME environment variable.";
throw new IllegalStateException(message);
}
}
compileJava.dependsOn checkJavaVersion
If you want the version to be checked for all tasks, you can add an assertion in build.gradle
to enforce it:
assert JavaVersion.current().isJava9Compatible(): "Java 9 or newer is required"
With Gradle 5.4.1, the failure looks like this:
$ ./gradlew --quiet build
FAILURE: Build failed with an exception.
* Where:
Build file '/home/codehearts/build.gradle' line: 15
* What went wrong:
A problem occurred evaluating root project 'Codehearts'.
> Java 9 or newer is required. Expression: org.gradle.api.JavaVersion.current().isJava9Compatible()
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 3s
You can also check exact versions if needed:
assert JavaVersion.current().isJava9(): "Java 9 is required"
Answer to self, and thanks to @JBNizet for providing the initial solution...
The solution is indeed to use JavaVersion
, and it happens that both sourceCompatibility
and targetCompatibility
accept a JavaVersion
as an argument...
Therefore the build file has become this:
def javaVersion = JavaVersion.VERSION_1_7;
sourceCompatibility = javaVersion;
targetCompatibility = javaVersion; // defaults to sourceCompatibility
And then the task:
task enforceVersion << {
def foundVersion = JavaVersion.current();
if (foundVersion != javaVersion)
throw new IllegalStateException("Wrong Java version; required is "
+ javaVersion + ", but found " + foundVersion);
}
compileJava.dependsOn(enforceVersion);
And it works:
$ ./gradlew clean compileJava
:clean UP-TO-DATE
:enforceVersion FAILED
FAILURE: Build failed with an exception.
* Where:
Build file '/home/fge/src/perso/grappa-tracer-backport/build.gradle' line: 55
* What went wrong:
Execution failed for task ':enforceVersion'.
> Wrong Java version; required is 1.7, but found 1.8