Find the first Class in the inheritance hierarchy of the specified clazz (including the specified clazz itself) - Java Reflection

Java examples for Reflection:Class

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Description

Find the first Class in the inheritance hierarchy of the specified clazz (including the specified clazz itself)

Demo Code


import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;

public class Main{

    /**/* ww w .java2  s  .  c o  m*/
     * Find the first {@link Class} in the inheritance hierarchy of the specified <code>clazz</code>
     * (including the specified <code>clazz</code> itself) which declares an annotation for the
     * specified <code>annotationType</code>, or <code>null</code> if not found. If the supplied
     * <code>clazz</code> is <code>null</code>, <code>null</code> will be returned.
     * <p>If the supplied <code>clazz</code> is an interface, only the interface itself will be checked;
     * the inheritance hierarchy for interfaces will not be traversed.
     * <p>The standard {@link Class} API does not provide a mechanism for determining which class
     * in an inheritance hierarchy actually declares an {@link Annotation}, so we need to handle
     * this explicitly.
     * @param annotationType the Class object corresponding to the annotation type
     * @param clazz the Class object corresponding to the class on which to check for the annotation,
     * or <code>null</code>
     * @return the first {@link Class} in the inheritance hierarchy of the specified <code>clazz</code>
     * which declares an annotation for the specified <code>annotationType</code>, or <code>null</code>
     * if not found
     * @see Class#isAnnotationPresent(Class)
     * @see Class#getDeclaredAnnotations()
     */
    public static Class<?> findAnnotationDeclaringClass(
            Class<? extends Annotation> annotationType, Class<?> clazz) {
        Assert.notNull(annotationType, "Annotation type must not be null");
        if (clazz == null || clazz.equals(Object.class)) {
            return null;
        }
        return (isAnnotationDeclaredLocally(annotationType, clazz)) ? clazz
                : findAnnotationDeclaringClass(annotationType,
                        clazz.getSuperclass());
    }
    /**
     * Determine whether an annotation for the specified <code>annotationType</code> is
     * declared locally on the supplied <code>clazz</code>. The supplied {@link Class}
     * may represent any type.
     * <p>Note: This method does <strong>not</strong> determine if the annotation is
     * {@link java.lang.annotation.Inherited inherited}. For greater clarity regarding inherited
     * annotations, consider using {@link #isAnnotationInherited(Class, Class)} instead.
     * @param annotationType the Class object corresponding to the annotation type
     * @param clazz the Class object corresponding to the class on which to check for the annotation
     * @return <code>true</code> if an annotation for the specified <code>annotationType</code>
     * is declared locally on the supplied <code>clazz</code>
     * @see Class#getDeclaredAnnotations()
     * @see #isAnnotationInherited(Class, Class)
     */
    public static boolean isAnnotationDeclaredLocally(
            Class<? extends Annotation> annotationType, Class<?> clazz) {
        Assert.notNull(annotationType, "Annotation type must not be null");
        Assert.notNull(clazz, "Class must not be null");
        boolean declaredLocally = false;
        for (Annotation annotation : Arrays.asList(clazz
                .getDeclaredAnnotations())) {
            if (annotation.annotationType().equals(annotationType)) {
                declaredLocally = true;
                break;
            }
        }
        return declaredLocally;
    }
}

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