How Do I Generate an Annotation Without a Name with JavaPoet?

Question

Suppose that I want to annotate a class with something like @RunWith(AndroidJUnit4.class). The general JavaPoet recipe would be:

  private static ClassName RUN_WITH=ClassName.get("org.junit.runner", "RunWith");
  private static ClassName ANDROID_JUNIT4=ClassName.get("android.support.test.runner", "AndroidJUnit4");

  private TypeSpec buildTestClass() {
    return TypeSpec.classBuilder("MainActivityTest")
      .addModifiers(Modifier.PUBLIC)
      .addAnnotation(AnnotationSpec.builder(RUN_WITH)
        .addMember(null, "$T.class", ANDROID_JUNIT4)
        .build())
      .build();
  }

However, the two addMember() methods on AnnotationSpec.Builder each take a member name... and I do not want a name. I tried null, as shown above, and that generates:

@RunWith(
    null = AndroidJUnit4.class
)

So... how do we generate an "anonymous" (or whatever the proper term is for a single-unnamed-member) annotation?

score 7 · Accepted Answer · answered Dec 25 '17 at 22:08

The magic name to use is value:

  private static ClassName RUN_WITH=ClassName.get("org.junit.runner", "RunWith");
  private static ClassName ANDROID_JUNIT4=ClassName.get("android.support.test.runner", "AndroidJUnit4");

  private TypeSpec buildTestClass() {
    return TypeSpec.classBuilder("MainActivityTest")
      .addModifiers(Modifier.PUBLIC)
      .addAnnotation(AnnotationSpec.builder(RUN_WITH)
        .addMember("value", "$T.class", ANDROID_JUNIT4)
        .build())
      .build();
  }

This generates @RunWith(AndroidJUnit4.class) as desired.

How Do I Generate an Annotation Without a Name with JavaPoet?

1 Answers1