SourceSetOutput

A collection of all output directories (compiled classes, processed resources, etc.) - notice that SourceSetOutput extends FileCollection.

Provides output information of the source set. Allows configuring the default output dirs and specify additional output dirs.

plugins {
    id 'java'
}

sourceSets {
  main {
    //if you truly want to override the defaults:
    output.resourcesDir = file('out/bin')
    // Compiled Java classes should use this directory
    java.destinationDirectory.set(file('out/bin'))
  }
}

Working with generated resources.

In general, we recommend generating resources into folders different than the regular resourcesDir and classesDirs. Usually, it makes the build easier to understand and maintain. Also it gives some additional benefits because other Gradle plugins can take advantage of the output dirs 'registered' in the SourceSet.output. For example: Java plugin will use those dirs in calculating class paths and for jarring the content; IDEA and Eclipse plugins will put those folders on relevant classpath.

An example how to work with generated resources:

plugins {
  id 'java'
}

def generateResourcesTask = tasks.register("generate-resources", GenerateResourcesTask) {
  resourcesDir.set(layout.buildDirectory.dir("generated-resources/main"))
}

// Include all outputs of the `generate-resources` task as outputs of the main sourceSet.
sourceSets {
  main {
    output.dir(generateResourcesTask)
  }
}

abstract class GenerateResourcesTask extends DefaultTask {
  @OutputDirectory
  abstract DirectoryProperty getResourcesDir()

  @TaskAction
  def generateResources() {
    def generated = resourcesDir.file("myGeneratedResource.properties").get().asFile
    generated.text = "message=Stay happy!"
  }
}

Find more information in SourceSetOutput.dir(java.lang.Object) and SourceSetOutput.getDirs()