将数组作为 JavaPoet 中注释参数的值传递

Question

Using JavaPoet I'm trying to annotate a class with an annotation which has an array as a parameter value ie

@MyCustom(param = { Bar.class, Another.class })
class Foo { 
}

I use AnnotationSpec.builder and its addMember() method:

List<TypeMirror> moduleTypes = new ArrayList<>(map.keySet());
AnnotationSpec annotationSpec = AnnotationSpec.builder(MyCustom.class)
   .addMember("param", "{ $T[] } ", moduleTypes.toArray() )
   .build();
builder.addAnnotation(annotationSpec);

Answer 1

Maybe not an optimal solution but passing an array to an annotation in JavaPoet can be done in the following way:

List<TypeMirror> moduleTypes = new ArrayList<>(map.keySet());
CodeBlock.Builder codeBuilder  = CodeBlock.builder();
boolean arrayStart = true;
codeBuilder.add("{ ");
for (TypeMirror modType: moduleTypes)
    if (!arrayStart)
        codeBuilder.add(" , ");
    arrayStart = false;
    codeBuilder.add("$T.class", modType);
codeBuilder.add(" }");

AnnotationSpec annotationSpec = AnnotationSpec.builder(MyCustom.class)
    .addMember("param", codeBuilder.build() )
    .build();
builder.addAnnotation(annotationSpec);

Answer 2

CodeBlock has a joining collector, and you can use that to stream this, doing something like the following (if for instance this was an enum). You can do it for any types, just the map would change.

AnnotationSpec.builder(MyCustom.class)
   .addMember(
      "param",
      "$L",
      moduleTypes.stream()
         .map(type -> CodeBlock.of("$T.$L", MyCustom.class, type))
         .collect(CodeBlock.joining(",", "{", "}")))
   .build()