How to add gradle generated source folder to Eclipse project? - gradle

Question

My gradle project generates some java code inside gen/main/java using annotation processor. When I import this project into Eclipse, Eclipse will not automatically add gen/main/java as source folder to buildpath. I can do it manually. But is there a way to automate this?
Thanks.

Answer 1

You can easily add the generated folder manually to the classpath by
eclipse {
classpath {
file.whenMerged { cp ->
cp.entries.add( new org.gradle.plugins.ide.eclipse.model.SourceFolder('gen/main/java', null) )
}
}
}
whereby null as a second constructor arg means that Eclipse should put the compiled "class" files within the default output folder. If you want to change this, just provide a String instead, e.g. 'bin-gen'.

Answer 2

I think it's a little bit cleaner just to add a second source directory to the main source set.
Add this to your build.gradle:
sourceSets {
main {
java {
srcDirs += ["src/gen/java"]
}
}
}
This results in the following line generated in your .classpath:
<classpathentry kind="src" path="src/gen/java"/>
I've tested this with Gradle 4.1, but I suspect it'd work with older versions as well.

Answer 3

Andreas' answer works if you generate Eclipse project from command line using gradle cleanEclipse eclipse. If you use STS Eclipse Gradle plugin, then you have to implement afterEclipseImport task. Below is my full working snippet:
project.ext {
genSrcDir = projectDir.absolutePath + '/gen/main/java'
}
compileJava {
options.compilerArgs += ['-s', project.genSrcDir]
}
compileJava.doFirst {
task createGenDir << {
ant.mkdir(dir: project.genSrcDir)
}
createGenDir.execute()
println 'createGenDir DONE'
}
eclipse.classpath.file.whenMerged {
classpath - >
def genSrc = new org.gradle.plugins.ide.eclipse.model.SourceFolder('gen/main/java', null)
classpath.entries.add(genSrc)
}
task afterEclipseImport(description: "Post processing after project generation", group: "IDE") {
doLast {
compileJava.execute()
def classpath = new XmlParser().parse(file(".classpath"))
new Node(classpath, "classpathentry", [kind: 'src', path: 'gen/main/java']);
def writer = new FileWriter(file(".classpath"))
def printer = new XmlNodePrinter(new PrintWriter(writer))
printer.setPreserveWhitespace(true)
printer.print(classpath)
}
}