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}