import java.lang.annotation.Annotation;

import java.util.Map;

import javax.annotation.processing.ProcessingEnvironment;

import javax.lang.model.element.ExecutableElement;

import javax.lang.model.element.TypeElement;

 * @see LayerGeneratingProcessor

    /**

     * An exception with an associated annotation.

     * Convenience constructor which locates an annotation on the erroneous element for you.

     * @param message a detail message which could be reported to the user

     * @param erroneousElement the associated element

     * @param processingEnv the processing environment passed to the processor

     * @param erroneousAnnotation the type of the annotation on the element

     * @see Messager#printMessage(javax.tools.Diagnostic.Kind, CharSequence, Element, AnnotationMirror)

     */

    public LayerGenerationException(String message, Element erroneousElement, ProcessingEnvironment processingEnv,

            Class<? extends Annotation> erroneousAnnotation) {

        this(message, erroneousElement, processingEnv, erroneousAnnotation, (String) null);

    }

    /**

     * An exception with an associated annotation value.

     * Convenience constructor which locates an annotation and its value on the erroneous element for you.

     * @param message a detail message which could be reported to the user

     * @param erroneousElement the associated element

     * @param processingEnv the processing environment passed to the processor

     * @param erroneousAnnotation the type of the annotation on the element

     * @param erroneousAnnotationValue the name of a method in that annotation

     * @see Messager#printMessage(javax.tools.Diagnostic.Kind, CharSequence, Element, AnnotationMirror, AnnotationValue)

     */

    public LayerGenerationException(String message, Element erroneousElement, ProcessingEnvironment processingEnv,

            Class<? extends Annotation> erroneousAnnotation, String erroneousAnnotationValue) {

        super(message);

        this.erroneousElement = erroneousElement;

        if (erroneousAnnotationValue != null) {

            try {

                erroneousAnnotation.getMethod(erroneousAnnotationValue);

            } catch (NoSuchMethodException x) {

                throw new IllegalArgumentException("No such method " + erroneousAnnotationValue + " in " + erroneousAnnotation);

            } catch (SecurityException x) {/* ignore? */}

        }

        this.erroneousAnnotation = findAnnotationMirror(erroneousElement, processingEnv, erroneousAnnotation);

        this.erroneousAnnotationValue = this.erroneousAnnotation != null && erroneousAnnotationValue != null ?

            findAnnotationValue(this.erroneousAnnotation, erroneousAnnotationValue) : null;

    }

    private static AnnotationMirror findAnnotationMirror(Element element, ProcessingEnvironment processingEnv, Class<? extends Annotation> annotation) {

        for (AnnotationMirror ann : element.getAnnotationMirrors()) {

            if (processingEnv.getElementUtils().getBinaryName((TypeElement) ann.getAnnotationType().asElement()).

                    contentEquals(annotation.getName())) {

                return ann;

            }

        }

        return null;

    }

    private AnnotationValue findAnnotationValue(AnnotationMirror annotation, String name) {

        for (Map.Entry<? extends ExecutableElement,? extends AnnotationValue> entry : annotation.getElementValues().entrySet()) {

            if (entry.getKey().getSimpleName().contentEquals(name)) {

                return entry.getValue();

            }

        }

        return null;

    }