Building with Intellij 2017.2 /out directory duplicates files in /build directory

Question

After updating to Intellij 2017.2, building my project creates an /out directory that contains generated source files and resource files. These files duplicate files that are already contained in /build and result in duplicate class compiler errors for the generated classes. Any ideas on a fix I need in Gradle or IntelliJ?

Monologue

Answer 1

IntelliJ IDEA is no longer sharing the output with Gradle, please see this ticket for details.

You can either override it via the following configuration:

allprojects {
 apply plugin: 'idea'
 idea {
   module {
     outputDir file('build/classes/main')
     testOutputDir file('build/classes/test')
   }
 }
 if(project.convention.findPlugin(JavaPluginConvention)) {
   // Change the output directory for the main and test source sets back to the old path
   sourceSets.main.output.classesDir = new File(buildDir, "classes/main")
   sourceSets.test.output.classesDir = new File(buildDir, "classes/test")
 }
}

or delegate the build to Gradle: File | Settings | Build, Execution, Deployment | Build Tools | Gradle | Runner => Delegate IDE build/run actions to gradle.

Geotaxis

Over in this other answer you say not to use the idea plugin. Which is it? #42500117 – Unlucky

@Unlucky don't mix up gradle idea command line which generates the project and idea plug-in which is used when IntelliJ IDEA is importing the project, these are not related and produce different project files. – Geotaxis

Delegating IDE build/run actions to gradle is much slower though. :( – Vin

The whole point of using an IDE with a script like Gradle or Maven was that the IDE could pick up the gradle scripts and would quickly build the project with minimal fuss. But if you have to build the gradle script every time, all your actions become slow. I feel sorry, you are making a very useful tool useless. – Killing

@Killing you don't have to delegate the build to Gradle, it's just one of the options. By default the build is performed by IntelliJ IDEA and is usually faster than Gradle. – Geotaxis

You have two output folders now. The script itself will build everything in the build folder. So if you want some taks to generate some java classes using gradle, they will always be generated in the build folder. And the ide in out folder. You cant manually make it source folder as every gradle build will reset your custom settings. Only the explicit source sets are compiled by the ide, the generated sets are not even clickable or traversable. Previously in 2017 at least i could add a fake source as build/classes/... And ide would find it, now it wont any more. It's becoming a mess. – Killing

The problem with this is the IntelliJ does not perform resource filtering so running say spring boot with resourceFiltering for yml files your run hen fails as tokens are not replaced by IntelliJ, What fun – Harangue

@Harangue In your case, I think Delegate IDE build/run actions to gradle. is the best option. – Quadrangular

Answer 2

File | Project Structure | Project Settings | Modules | Paths tab | Compiler output

Select 'Inherit project compile output path' to continue using /build for build artifacts

Monologue

But as soon as you run gradle build the build directory will be back with all its duplicates – Algebraic

IntelliJ IDEA is no longer sharing the output with Gradle, please see youtrack.jetbrains.com/issue/IDEA-175172 for details. – Geotaxis

@CrazyCoder, thanks for interesting link to youtrack issue. Discussion there suggests (among other things) to try delegating IDEA build/run to Gradle. I had similar problems with duplicate (yet different) structure of out directory, but after setting File | Settings | Build, Execution, Deployment | Build Tools | Gradle | Runner => Delegate IDE build/run actions to gradle I got much better results. Maybe not for everyone, but may be the way for many. – Patrilineal

Answer 3

Here is my understanding:

Basically, this is a work-around for an incompatibility issue between Gradle build path and IDEA output path.

• the issue is - https://github.com/gradle/gradle/issues/2315
• the solution is - keep these two directories seperate, therefore you have two (out/ and build/) https://youtrack.jetbrains.com/issue/IDEA-189063

Lashundalasker