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JSONAPI-Converter is a library that provides means for integrating with services using JSON API specification.

There is a newer version: 0.14

package com.github.jasminb.jsonapi;

import com.github.jasminb.jsonapi.annotations.Type;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
 * Various utility methods that simplify JAVA reflection actions.
 *
 * @author jbegic
 */
public class ReflectionUtils {

	private ReflectionUtils() {
		// Private CTOR
	}

	/**
	 * Returns all field from a given class that are annotated with provided annotation type.
	 * @param clazz source class
	 * @param annotation target annotation
	 * @param checkSuperclass if true, method will follow class hierarchy to look for fields with target annotation
	 * @return list of fields or empty collection in case no fields were found
	 */
	public static List getAnnotatedFields(Class clazz, Class annotation,
												 boolean checkSuperclass) {
		Field [] fields = clazz.getDeclaredFields();

		List result = new ArrayList<>();

		for (Field field : fields) {
			if (field.isAnnotationPresent(annotation)) {
				result.add(field);
			}
		}

		if (checkSuperclass && clazz.getSuperclass() != null && !clazz.getSuperclass().equals(Object.class)) {
			result.addAll(getAnnotatedFields(clazz.getSuperclass(), annotation, true));
		}

		return result;
	}

	/**
	 * Returns the type name defined using Type annotation on provided class.
	 * @param clazz type class
	 * @return name of the type or null in case Type annotation is not present
	 */
	public static String getTypeName(Class clazz) {
		Type typeAnnotation = clazz.getAnnotation(Type.class);
		return typeAnnotation != null ? typeAnnotation.value() : null;
	}

	public static Class getFieldType(Field field) {
		Class targetType = field.getType();

		if (Collection.class.isAssignableFrom(targetType)) {
			ParameterizedType stringListType = (ParameterizedType) field.getGenericType();
			targetType = (Class) stringListType.getActualTypeArguments()[0];
		}

		return targetType;
	}
}