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/*
 * Licensed to the Nervousync Studio (NSYC) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.nervousync.utils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * @author Steven Wee	[email protected]
 * @version $Revision: 1.0 $ $Date: Jan 13, 2010 4:27:49 PM $
 */
public final class CollectionUtils {
	
	private CollectionUtils() {
		
	}

	/**
	 * Sort number collection
	 * @param collection	collection
	 * @return				Sorted collection
	 */
	public static List sort(Collection collection) {
		List returnList = new ArrayList();
		Iterator iterator = collection.iterator();
		while (iterator.hasNext()) {
			returnList.add(iterator.next());
		}
		
		Collections.sort(returnList);
		
		return returnList;
	}

	/**
	 * Sort number collection and reverse result
	 * @param collection	collection
	 * @return				Sorted and reverse collection
	 */
	public static List sortAndReverse(Collection collection) {
		List returnList = new ArrayList();
		Iterator iterator = collection.iterator();
		while (iterator.hasNext()) {
			returnList.add(iterator.next());
		}
		
		Collections.sort(returnList);
		Collections.reverse(returnList);
		
		return returnList;
	}
	
	/**
	 * Return true if the supplied Collection is null
	 * or empty. Otherwise, return false.
	 * @param collection the Collection to check
	 * @return whether the given Collection is empty
	 */
	public static boolean isEmpty(Collection collection) {
		return (collection == null || collection.isEmpty());
	}

	/**
	 * Return true if the supplied Map is null
	 * or empty. Otherwise, return false.
	 * @param map the Map to check
	 * @return whether the given Map is empty
	 */
	public static boolean isEmpty(Map map) {
		return (map == null || map.isEmpty());
	}

	/**
	 * Convert the supplied array into a List. A primitive array gets
	 * converted into a List of the appropriate wrapper type.
	 * 

A null source value will be converted to an * empty List. * @param source the (potentially primitive) array * @return the converted List result * @see ObjectUtils#toObjectArray(Object) */ public static List arrayToList(Object source) { return Arrays.asList(ObjectUtils.toObjectArray(source)); } /** * Convert arrays to list * @param a arrays * @param T * @return Convert list */ public static List asList(T[] a) { return Arrays.asList(a); } /** * Merge the given array into the given Collection. * @param array the array to merge (may be null) * @param collection the target Collection to merge the array into */ public static void mergeArrayIntoCollection(Object array, Collection collection) { if (collection == null) { throw new IllegalArgumentException("Collection must not be null"); } Object[] arr = ObjectUtils.toObjectArray(array); for (int i = 0; i < arr.length; i++) { collection.add(arr[i]); } } /** * Merge the given Properties instance into the given Map, * copying all properties (key-value pairs) over. *

Uses Properties.propertyNames() to even catch * default properties linked into the original Properties instance. * @param props the Properties instance to merge (may be null) * @param map the target Map to merge the properties into */ public static void mergePropertiesIntoMap(Properties props, Map map) { if (map == null) { throw new IllegalArgumentException("Map must not be null"); } if (props != null) { for (Enumeration en = props.propertyNames(); en.hasMoreElements();) { String key = (String) en.nextElement(); map.put(key, props.getProperty(key)); } } } /** * Check whether the given Iterator contains the given element. * @param iterator the Iterator to check * @param element the element to look for * @return true if found, false else */ public static boolean contains(Iterator iterator, Object element) { if (iterator != null) { while (iterator.hasNext()) { Object candidate = iterator.next(); if (ObjectUtils.nullSafeEquals(candidate, element)) { return true; } } } return false; } /** * Check whether the given Enumeration contains the given element. * @param enumeration the Enumeration to check * @param element the element to look for * @return true if found, false else */ public static boolean contains(Enumeration enumeration, Object element) { if (enumeration != null) { while (enumeration.hasMoreElements()) { Object candidate = enumeration.nextElement(); if (ObjectUtils.nullSafeEquals(candidate, element)) { return true; } } } return false; } /** * Check whether the given Collection contains the given element instance. *

Enforces the given instance to be present, rather than returning * true for an equal element as well. * @param collection the Collection to check * @param element the element to look for * @return true if found, false else */ public static boolean containsInstance(Collection collection, Object element) { if (collection != null) { for (Iterator it = collection.iterator(); it.hasNext();) { Object candidate = it.next(); if (candidate == element) { return true; } } } return false; } /** * Return true if any element in 'candidates' is * contained in 'source'; otherwise returns false. * @param source the source Collection * @param candidates the candidates to search for * @return whether any of the candidates has been found */ public static boolean containsAny(Collection source, Collection candidates) { if (isEmpty(source) || isEmpty(candidates)) { return false; } for (Iterator it = candidates.iterator(); it.hasNext();) { if (source.contains(it.next())) { return true; } } return false; } /** * Return the first element in 'candidates' that is contained in * 'source'. If no element in 'candidates' is present in * 'source' returns null. Iteration order is * {@link Collection} implementation specific. * @param source the source Collection * @param candidates the candidates to search for * @return the first present object, or null if not found */ public static Object findFirstMatch(Collection source, Collection candidates) { if (isEmpty(source) || isEmpty(candidates)) { return null; } for (Iterator it = candidates.iterator(); it.hasNext();) { Object candidate = it.next(); if (source.contains(candidate)) { return candidate; } } return null; } /** * Find a single value of the given type in the given Collection. * @param collection the Collection to search * @param type the type to look for * @return a value of the given type found if there is a clear match, * or null if none or more than one such value found */ public static Object findValueOfType(Collection collection, Class type) { if (isEmpty(collection)) { return null; } Object value = null; for (Iterator it = collection.iterator(); it.hasNext();) { Object obj = it.next(); if (type == null || type.isInstance(obj)) { if (value != null) { // More than one value found... no clear single value. return null; } value = obj; } } return value; } /** * Find a single value of one of the given types in the given Collection: * searching the Collection for a value of the first type, then * searching for a value of the second type, etc. * @param collection the collection to search * @param types the types to look for, in prioritized order * @return a value of one of the given types found if there is a clear match, * or null if none or more than one such value found */ public static Object findValueOfType(Collection collection, Class[] types) { if (isEmpty(collection) || ObjectUtils.isEmpty(types)) { return null; } for (int i = 0; i < types.length; i++) { Object value = findValueOfType(collection, types[i]); if (value != null) { return value; } } return null; } /** * Determine whether the given Collection only contains a single unique object. * @param collection the Collection to check * @return true if the collection contains a single reference or * multiple references to the same instance, false else */ public static boolean hasUniqueObject(Collection collection) { if (isEmpty(collection)) { return false; } boolean hasCandidate = false; Object candidate = null; for (Iterator it = collection.iterator(); it.hasNext();) { Object elem = it.next(); if (!hasCandidate) { hasCandidate = true; candidate = elem; } else if (candidate != elem) { return false; } } return true; } }