org.butor.utils.DiffUtils Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of butor-utils Show documentation

This project is an utility module, contains utility functions for the other modules of the framework.

There is a newer version: 1.0.29

/**
 * Copyright 2013-2017 butor.com
 *
 * 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 org.butor.utils;

import java.lang.reflect.Field;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

import com.google.common.base.Throwables;

public class DiffUtils {
	/**
	 * Returns an alphabetically sorted set of fields names that have differences in their value 
	 * between two objects.
	 * 
	 * It is very important that the field types of the object you are comparing override equals() and hashcode()
	 * otherwise the class might detect a difference where they are not 
	 *  
	 * @param o1 object
	 * @param o2 object
	 * @return set of string representing the difference between o1 and o2
	 */
	public static Set getDifferences(Object o1, Object o2) {
		Set diffSet = new TreeSet();
		Map mapObject1 = getFieldMap(o1);
		Map mapObject2 = getFieldMap(o2);
		
		populateDiffSet(diffSet, mapObject1, mapObject2);
		populateDiffSet(diffSet, mapObject2, mapObject1);
		return diffSet;
	}

	private static void populateDiffSet(Set diffSet,
			Map map1, Map map2) {
		for (Entry entry : map1.entrySet()) {
			String fieldName = entry.getKey();
			Object v1 = entry.getValue();
			Object v2 = map2.get(fieldName);
			if ((v1 != null && !v1.equals(v2)) || (v2 != null && !v2.equals(v1))) {
				diffSet.add(fieldName);
			}
		}
	}

	private static Map getFieldMap(Object o1) {
		Map mapObject1 = new TreeMap();
		for (Field f : o1.getClass().getDeclaredFields()) {
			f.setAccessible(true);
			try {
				mapObject1.put(f.getName(), f.get(o1));
			} catch (Exception e) {
				Throwables.propagate(e);
			}
		}
		return mapObject1;
	}

}