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/**
 * Copyright (C) 2014 Dasasian ([email protected])
 *
 * 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.
 */
package com.dasasian.chok.util;

import org.I0Itec.zkclient.ExceptionUtil;

import java.lang.reflect.Field;

public class ClassUtil {

    /**
     * @param  the generic class
     * @param className the name of the class
     * @param instanceOfClass the instanceOfClass
     * @return the class object for a given class name
     */
    @SuppressWarnings("unchecked")
    public static  Class forName(String className, Class instanceOfClass) {
        try {
            Class loadedClass = Class.forName(className);
            if (!instanceOfClass.isAssignableFrom(loadedClass)) {
                throw new IllegalStateException("Class " + className + " does not implement " + instanceOfClass.getName());
            }
            return (Class) loadedClass;
        } catch (ClassNotFoundException e) {
            throw ExceptionUtil.convertToRuntimeException(e);
        }
    }

    /**
     * @param  the generic class
     * @param clazz the class
     * @return a new instance of the given class
     */
    public static  T newInstance(Class clazz) {
        try {
            return clazz.newInstance();
        } catch (Exception e) {
            throw new RuntimeException("could not instantiate class " + clazz.getName(), e);
        }
    }

    /**
     * @param object the object
     * @param fieldName the field name
     * @return the value of the (private) field of the given object with the given
     * name
     */
    public static Object getPrivateFieldValue(Object object, String fieldName) {
        return getPrivateFieldValue(object.getClass(), object, fieldName);
    }

    /**
     * @return the value of the (private) field of the given object declared in
     * the given class with the given name
     * @param clazz the class
     * @param object the object
     * @param fieldName  the name of the field
     */
    public static Object getPrivateFieldValue(Class clazz, Object object, String fieldName) {
        Field field = null;
        do {
            try {
                field = clazz.getDeclaredField(fieldName);
            } catch (NoSuchFieldException e) {
                // proceed with superclass
            }
            clazz = clazz.getSuperclass();
        } while (clazz != null);
        try {
            if (field == null) {
                throw new NoSuchFieldException("no field '" + fieldName + "' in object " + object);
            }
            field.setAccessible(true);
            return field.get(object);
        } catch (Exception e) {
            throw ExceptionUtil.convertToRuntimeException(e);
        }
    }

}