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Kuali Utilities
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/**
 * Copyright 2010-2014 The Kuali Foundation
 *
 * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
 *
 * 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 org.kuali.common.util;

import static com.google.common.base.Preconditions.checkState;
import static org.kuali.common.util.base.Precondition.checkNotNull;

import java.util.Objects;

import org.kuali.common.util.equality.Equatable;

public class ObjectUtils {

	/**
	 * 
	 * This method returns true if the toString() methods on both objects return matching strings AND both objects are the exact same runtime type.
	 * 
	 * 
	 * 
	 * Returns true immediately if instance==other (ie they are the same object).
	 * 
	 * 
	 * 
	 * Returns false immediately if other==null or is a different runtime type than instance.
	 * 
	 * 
	 * 
	 * If neither one is null, and both are the exact same runtime type, then compare the toString() methods
	 * 
	 * 
	 * @param instance
	 *            The object other is being compared to.
	 * @param other
	 *            The object being examined for equality with instance.
	 * 
	 * @throws NullPointerException
	 *             If instance is null or instance.toString() returns null
	 */
	public static boolean equalsByToString(Object instance, Object other) {
		checkNotNull(instance, "instance");

		// They are the same object
		if (instance == other) {
			return true;
		}

		if (notEqual(instance, other)) {
			return false; // Don't bother comparing the toString() methods
		} else {
			return instance.toString().equals(other.toString());
		}
	}

	/**
	 * 
	 * Return true if instance is definitely not equal to other.
	 * 
	 * 
	 * 
	 * If other is null OR a different runtime type than instance, return true
	 * 
	 * 
	 * @param instance
	 *            The object other is being compared to.
	 * @param other
	 *            The object being examined for equality with instance.
	 * 
	 * @throws NullPointerException
	 *             If instance is null
	 */
	public static boolean notEqual(Object instance, Object other) {
		checkNotNull(instance, "instance");
		if (other == null) {
			return true;
		} else {
			return instance.getClass() != other.getClass();
		}
	}

	public static  boolean equal(T instance, Object other) {
		checkNotNull(instance, "instance");
		if (instance == other) {
			return true;
		} else if (notEqual(instance, other)) {
			return false;
		} else {
			return equal(instance, (Equatable) other);
		}
	}

	private static boolean equal(Equatable instance, Equatable other) {
		Object[] values1 = instance.getEqualityValues();
		Object[] values2 = other.getEqualityValues();
		checkState(values1.length == values2.length, "value arrays must be the same. values1.length=%s values2.length=%s", values1.length, values2.length);
		for (int i = 0; i < values1.length; i++) {
			if (!Objects.equals(values1[i], values2[i])) {
				return false;
			}
		}
		return true;
	}

}