Java Reflection Annotation getAnnotation(Class clazz, Class annotationType)

Description

get Annotation

License

Apache License

Declaration

public static <T extends Annotation> T getAnnotation(Class<?> clazz, Class<T> annotationType) 

Method Source Code

//package com.java2s;
/*/*from w  w w  .  j a v  a  2s. c o  m*/
 * #%L
 * %%
 * Copyright (C) 2016 BMW Car IT GmbH
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import java.lang.annotation.Annotation;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import com.google.common.collect.Iterables;

public class Main {
    public static <T extends Annotation> T getAnnotation(Class<?> clazz, Class<T> annotationType) {
        Iterable<T> allAnnotations = Iterables.filter(getAnnotationsRecursive(clazz), annotationType);
        if (allAnnotations.iterator().hasNext()) {
            return allAnnotations.iterator().next();
        }
        return null;
    }

    public static Collection<Annotation> getAnnotationsRecursive(Class<?> clazz) {
        Collection<Annotation> allAnnotations = new HashSet<>();
        getAllAnnotations(clazz, allAnnotations);
        return allAnnotations;
    }

    private static void getAllAnnotations(Class<?> clazz, Collection<Annotation> result) {
        if (clazz == null) {
            return;
        }
        result.addAll(Arrays.asList(clazz.getDeclaredAnnotations()));
        for (Class<?> interfaceClass : clazz.getInterfaces()) {
            getAllAnnotations(interfaceClass, result);
        }

        getAllAnnotations(clazz.getSuperclass(), result);
    }
}

Related

1. getAnnotation(Class clazz, Class annotationClass)
2. getAnnotation(Class clazz, Class annotationClass)
3. getAnnotation(Class clazz, Class annotationClass)
4. getAnnotation(Class clazz, Class annotationType)
5. getAnnotation(Class clazz, Class annotationType)
6. getAnnotation(Class clazz, String fieldName, Class annotationClass)
7. getAnnotation(Class clazz, String name, Class[] types, Class annotationType)
8. getAnnotation(Class cls, Class annotationClass)
9. getAnnotation(Class cls, Class annotation)