Can AspectJ Achieve Annotation Inheritance for Interfaces and Their Methods?

Can AspectJ Emulate Annotation Inheritance for Interfaces and Their Methods?

Java annotation inheritance is restricted, with annotations defined on interfaces, methods, or annotations not inherited by implementing classes, overriding methods, or classes utilizing annotated annotations. This limitation applies to AspectJ, which operates within JVM constraints.

Solution: Emulating Annotation Inheritance in Specific Cases

While a general solution for annotation inheritance is unavailable, a workaround exists for specific interfaces or methods:

<code class="java">public aspect MarkerAnnotationInheritor {
  // Implementing classes inherit the marker annotation
  declare @type: MyInterface+ : @Marker;
  // Overriding 'two' method inherits the annotation
  declare @method : void MyInterface+.two() : @Marker;
}</code>

Implementation:

• ITDs (inter-type definitions) manually add the annotation to the interface and implementing/overriding classes/methods.
• The actual annotation on the interface or method can be removed.

Result:

The console log now prints:

execution(de.scrum_master.app.Application())
execution(void de.scrum_master.app.Application.two())

Alternative Solution:

The aspect can be embedded within the interface, consolidating the implementation in one location. Rename the file to .aj for compiler recognition.

<code class="java">// MyInterface.aj

public interface MyInterface {
  void one();
  void two();
  
  public static aspect MarkerAnnotationInheritor {
    declare @type: MyInterface+ : @Marker;
    declare @method : void MyInterface+.two() : @Marker;
  }
}</code>

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