Find the specified (meta-) annotation of given class. - Java java.lang.annotation

Java examples for java.lang.annotation:Class Annotation

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Description

Find the specified (meta-) annotation of given class.

Demo Code

/*/*from   w w  w  .ja v  a2s  .c  o m*/
 * ajUnit - Unit Testing AspectJ.
 *
 * Copyright (C) 2013-2014 Marko Umek (http://fail-early.com/contact)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */
//package com.java2s;
import java.lang.annotation.Annotation;

public class Main {


    /**
     * Find the specified (meta-)annotation of given class. If more then one annotation is present the first will be
     * returned.
     *
     * @param aClass  the class to be inspect.
     * @param annotationClass the annotation class to be found.
     * @param <T> the annotation type
     * @return the annotation instance of {@code annotationClass} or {@code null}.
     */
    public static <T extends Annotation> T findClassAnnotation(
            final Class<?> aClass, final Class<T> annotationClass) {
        T annotation = aClass.getAnnotation(annotationClass);
        if (annotation == null) {
            annotation = findMetaAnnotation(aClass.getAnnotations(),
                    annotationClass);
        }
        return annotation;
    }

    private static <T extends Annotation> T findMetaAnnotation(
            final Annotation[] annotations, final Class<T> annotationClass) {
        T metaAnnotation = null;
        for (Annotation annotation : annotations) {
            final Class<? extends Annotation> currentMetaAnnotation = annotation
                    .annotationType();
            metaAnnotation = currentMetaAnnotation
                    .getAnnotation(annotationClass);
            if (metaAnnotation != null) {
                break;
            }
        }

        return metaAnnotation;
    }
}

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