Cannot build Gradle project with Gradle Support plugin for NetBeans 8.1

Question

I started a learning project to get familiar with Gradle, Spring and Vaadin. So far, I successfully created basic CRUD functionality with the help of some Spring guides.

Now I want to import the project into NetBeans. I installed the Gradle Support plugin for NetBeans and cloned my repository into a new NetBeans project.

When I try to build or bootRun the project within NetBeans, it fails, telling me that the main class cannot be found. But when I build or bootRun directly from the command line using the gradle wrapper I loaded into the repository, it works fine.

I studied every single page of the Gradle Support plugin's wiki on GitHub but couldn't find any information relevant to my problem.

Here's the output I get when trying to run the project in NetBeans via the project's context menu action Tasks/build/build:

Executing: gradle :build

:compileJava UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:findMainClass FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':findMainClass'.
> Could not find property 'main' on task ':run'.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Total time: 1.957 secs



Build failure (see the Notifications window for stacktrace): gradle :build

I pasted the mentioned stacktrace to Gist.

And here's the output I get for the successful build executed from the command line on the very same project:

$ ./gradlew build
:compileJava UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:findMainClass
:jar
:bootRepackage
:assemble
:compileTestJava UP-TO-DATE
:processTestResources UP-TO-DATE
:testClasses UP-TO-DATE
:test UP-TO-DATE
:check UP-TO-DATE
:build

BUILD SUCCESSFUL

Total time: 11.673 secs

I have really no idea how to go on with this and would greatly appreciate any hints and I find it very odd that I get different results when running from command line and when running from within NetBeans. Shouldn't the NetBeans plugin just be calling the same commands that I use directly on the command line and that work fine?

Answer 1

I found two ways to fix this since.

a) Adding

if (!hasProperty('mainClass')) {
    ext.mainClass = 'org.foo.Bar'
}

to build.gradle.

b) Setting Options / Miscellaneous / Gradle / Task Execution / Automatic tasks to "NetBeans should not add tasks automatically".

This comment I found in a build.gradle file generated by NetBeans gave me the crucial hint:

// NetBeans will automatically add "run" and "debug" tasks relying on the
// "mainClass" property. You may however define the property prior executing
// tasks by passing a "-PmainClass=<QUALIFIED_CLASS_NAME>" argument.
//
// Note however, that you may define your own "run" and "debug" task if you
// prefer. In this case NetBeans will not add these tasks but you may rely on
// your own implementation.

Answer 2

I got the same error when using the latest version of spring-boot-gradle-plugin (1.3.1.RELEASE). After downgrading to 1.2.8.RELEASE the error disappeared.

There has been some configuration changes in 1.3.x, see under Gradle plugin here: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-1.3-Release-Notes

Maybe version resolution is different in NetBeans Gradle vs. command line. So you could try specify version 1.2.8, or update the config according to the 1.3 changes.