001/*
002 * oauth2-oidc-sdk
003 *
004 * Copyright 2012-2016, Connect2id Ltd and contributors.
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use
007 * this file except in compliance with the License. You may obtain a copy of the
008 * License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software distributed
013 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
014 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
015 * specific language governing permissions and limitations under the License.
016 */
017
018package com.nimbusds.oauth2.sdk.util;
019
020
021import java.util.Collection;
022
023
024/**
025 * Collection utilities.
026 */
027public final class CollectionUtils {
028        
029        
030        /**
031         * Returns {@code true} if the specified collection is {@code null} or
032         * empty.
033         *
034         * @param collection The collection. May be {@code null}.
035         *
036         * @return {@code true} if the collection is {@code null} or empty,
037         *         else {@code false}.
038         */
039        public static boolean isEmpty(final Collection<?> collection) {
040                
041                return collection == null || collection.isEmpty();
042        }
043        
044        
045        /**
046         * Returns {@code true} if the specified collection is not empty.
047         *
048         * @param collection The collection. May be {@code null}.
049         *
050         * @return {@code true} if the collection is not empty, else
051         *         {@code false}.
052         */
053        public static boolean isNotEmpty(final Collection<?> collection) {
054                
055                return collection != null && ! collection.isEmpty();
056        }
057        
058        
059        /**
060         * Returns {@code true} if the specified collection contains the
061         * specified item.
062         *
063         * @param collection The collection. May be {@code null}.
064         * @param item       The item. Should not be {@code null}.
065         *
066         * @return {@code true} if the collection is not empty and contains the
067         *         item, else {@code false}.
068         */
069        public static <T> boolean contains(final Collection<T> collection, final T item) {
070                
071                return isNotEmpty(collection) && collection.contains(item);
072        }
073        
074        
075        /**
076         * Returns {@code true} if the specified collections intersect.
077         *
078         * @param a The first collection. May be {@code null}.
079         * @param b The second collection. May be {@code null}.
080         *
081         * @return {@code true} if the collections intersect, else
082         *         {@code false}.
083         */
084        public static <T> boolean intersect(final Collection<T> a, final Collection<T> b) {
085                
086                if (isEmpty(a) || isEmpty(b)) {
087                        return false;
088                }
089                
090                for (T item: a) {
091                        if (b.contains(item)) {
092                                return true;
093                        }
094                }
095                
096                return false;
097        }
098        
099        
100        /**
101         * Prevents public instantiation.
102         */
103        private CollectionUtils() {}
104}