How do I set up Buck with Dagger & Butterknife?

Hello my fellow developers,

I'm trying to switch from Gradle to Buck and have problems setting it up with Dagger and Butterknife since they need annotation processing.

I found a few links and tutorials, but they are already a few (~4) years old and I thought there might be a little bit newer approach on doing things.

This is what I looked at already: https://github.com/ryan-endacott/android-buck-dagger-starter

Thanks in advance, Patrick

Buck supports annotation processing for Java-based rules (including android_library). Take a look at how Immutables are used in buck repository (link to source code):

1. First of all, you need to declare library jars:

    java_library(
        name = "immutables",
        exported_deps = [
            ":builder",
            ":value",
        ],
        visibility = [
            "PUBLIC",
        ],
    )

    prebuilt_jar(
        name = "value",
        binary_jar = "value-2.5.6.jar",
        source_jar = "value-2.5.6-sources.jar",
        licenses = [
            "COPYING",
        ],
    )

    prebuilt_jar(
        name = "builder",
        binary_jar = "builder-2.5.6.jar",
        source_jar = "builder-2.5.6-sources.jar",
        licenses = [
            "COPYING",
        ],
    )

2. Define annotation processor:

    java_annotation_processor(
        name = "processor",
        isolate_class_loader = True,
        processor_class = "org.immutables.value.internal.$processor$.$Processor",
        visibility = [
            "PUBLIC",
        ],
        deps = [
            ":immutables",
        ],
    )

3. You can then add this annotation processor to the list of plugins of the targets:

    java_library(
        name = "target",
        plugins = [
            "//third-party/java/immutables:processor",
        ],
        deps = [
            ...
        ],
        ...
    )

Buck repository contains a custom rule (java_immutables_library) that adds this annotation processor so that developers don't need to specify plugins on every target. You can probably use similar approach.