Java Reflection Field Find findFieldWithAnnotation(String fieldName, Class clazz, Class annotationType)

Description

Look for a field based on his name and a given Annotation in a class.

License

LGPL

Parameter

Parameter	Description
fieldName	The field name.
clazz	The scanned class.
annotationType	The expected annotation type.

Return

The field if found, null if not.

Declaration

public static Field findFieldWithAnnotation(String fieldName, Class<?> clazz,
        Class<? extends Annotation> annotationType) 

Method Source Code

//package com.java2s;
//License from project: LGPL 

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main {
    /**// w  w w .j  a  va  2s  .c om
     * Look for a field based on his name and a given Annotation in a class.
     *
     * @param fieldName      The field name.
     * @param clazz          The scanned class.
     * @param annotationType The expected annotation type.
     * @return The field if found, null if not.
     */
    public static Field findFieldWithAnnotation(String fieldName, Class<?> clazz,
            Class<? extends Annotation> annotationType) {
        Field field = getField(fieldName, clazz);
        if (field != null && field.isAnnotationPresent(annotationType)) {
            return field;
        }

        return null;
    }

    /**
     * Find a field with the given name and class annotation
     *
     * @param fieldName The field name
     * @param clazz     The annotation class.
     * @return the field, null if not found.
     */
    public static Field getField(String fieldName, Class<?> clazz) {
        List<Field> fields = getAllFields(clazz);
        for (Field field : fields) {
            if (field.getName().equals(fieldName)) {
                return field;
            }
        }
        return null;
    }

    /**
     * Return all fields of the class, including inherited one.
     *
     * @param clazz The class.
     * @return The list of all fields.
     */
    public static List<Field> getAllFields(Class<?> clazz) {
        List<Field> currentClassFields = new ArrayList<>(Arrays.asList(clazz.getDeclaredFields()));
        Class<?> parentClass = clazz.getSuperclass();

        if (parentClass != null && !(parentClass.equals(Object.class))) {
            List<Field> parentClassFields = getAllFields(parentClass);
            currentClassFields.addAll(parentClassFields);
        }

        return currentClassFields;
    }
}

Related

1. findFieldsAnnotatedWith(Class annotation, Class parentClass)
2. findFieldsAnnotatedWith(final Class type, final Class annotation)
3. findFieldsOfClass(Class target, Object o, String path, Logger log, Set done)
4. findFieldToInject(Class target, String name, Class source)
5. findFieldType(Field field, Class concreteClass)