CollectionUtils.java Source code

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Here is the source code for CollectionUtils.java

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
 *
 *      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.
 */

/**
 * 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 = it.next();
            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());
    }
}