Attach javapoet / javawriter to an existing class

I've been experimenting with code generation in annotation processors

Consider the following code and add a constructor that contains the statement

private void addRegister(ExecutableElement el) {
    MethodSpec builder = MethodSpec.constructorBuilder().addStatement("$T.register(this)",EventExecutor.class).build();
    TypeSpec spec = TypeSpec.classBuilder(el.getEnclosingElement().getSimpleName().toString()).addOriginatingElement(el).addMethod(builder).build();
    JavaFile file = JavaFile.builder(pEnv.getElementUtils().getPackageOf(el.getEnclosingElement()).getQualifiedName().toString(),spec).build();
    pEnv.getMessager().printMessage(Diagnostic.Kind.NOTE,file.toString());
}

Now, when an executable element named "BLA" is given in the "test" class, the results are as follows:

class Test {
   test() {
     EventExecutor.register(this);
   }
}

But this class already exists. I want to append the constructor to the existing code instead of creating this new class here

Existing code:

public class Test {

    @Event
    public void bla(TestEvent event) {

    }
}

Can I do this?

Solution

No, the annotation processor cannot modify existing code They can only generate new code After reading this question, the problem is the same