Return the first element in 'candidates' that is contained in source : Collection « Collections Data Structure « Java

Return the first element in 'candidates' that is contained in source

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

 * Copyright 2002-2007 the original author or authors.
 * 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

 * Miscellaneous collection utility methods.
 * Mainly for internal use within the framework.
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @since 1.1.3
abstract class CollectionUtils {

   * Return the first element in '<code>candidates</code>' that is contained in
   * '<code>source</code>'. If no element in '<code>candidates</code>' is present in
   * '<code>source</code>' returns <code>null</code>. 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 <code>null</code> 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 =;
      if (source.contains(candidate)) {
        return candidate;
    return null;

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


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