Using AutoValue with Bazel

AutoValue is a really handy library to eliminate boilerplate in your Java code. Basically, if you have a “plain old Java object” with some fields, there are all sorts of things you need to do to make it work “good,” e.g., implement equals and hashCode to use it in collections, make all of its fields final (and optimally immutable), make the fields private and accessed through getters, etc. AutoValue generates all of that for you.

To get AutoValue work with Bazel, I ended up modifying cushon’s example. There were a couple of things I didn’t like about it, since I didn’t want the AutoValue library to live in my project’s BUILD files. I set it up so it was defined in the AutoValue project, so I figured I’d share what I came up with.

In your WORKSPACE file, add a new_http_archive for the AutoValue jar. I’m using the one in Maven, but not using maven_jar because I want to override the BUILD file to provide AutoValue as both a Java library and a Java plugin:

new_http_archive(
    name = "auto_value",
    url = "http://repo1.maven.org/maven2/com/google/auto/value/auto-value/1.3/auto-value-1.3.jar",
    build_file_content = """
java_import(
    name = "jar",
    jars = ["auto-value-1.3.jar"],
)

java_plugin(
    name = "autovalue-plugin",
    generates_api = 1,
    processor_class = "com.google.auto.value.processor.AutoValueProcessor",
    deps = [":jar"],
)

java_library(
    name = "processor",
    exported_plugins = [":autovalue-plugin"],
    exports = [":jar"],
    visibility = ["//visibility:public"],
)
""",
)

Then you can depend on @auto_value//:processor in any java_library target:

java_library(
    name = "project",
    srcs = ["Project.java"],
    deps = ["@auto_value//:processor"],
)

…and Bob’s your uncle.