001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.functor.core.collection; 018 019 import java.io.Serializable; 020 import java.lang.reflect.Array; 021 import java.util.Collection; 022 023 import org.apache.commons.functor.BinaryPredicate; 024 import org.apache.commons.functor.UnaryPredicate; 025 import org.apache.commons.functor.adapter.RightBoundPredicate; 026 027 /** 028 * A {@link BinaryPredicate} that checks to see if the 029 * specified object is an element of the specified 030 * Collection. 031 * 032 * @since 1.0 033 * @version $Revision: 1170771 $ $Date: 2011-09-14 21:07:22 +0200 (Wed, 14 Sep 2011) $ 034 * @author Jason Horman (jason@jhorman.org) 035 * @author Rodney Waldhoff 036 */ 037 public final class IsElementOf<L, R> implements BinaryPredicate<L, R>, Serializable { 038 // static members 039 //--------------------------------------------------------------- 040 041 /** 042 * serialVersionUID declaration. 043 */ 044 private static final long serialVersionUID = -7639051806015321070L; 045 private static final IsElementOf<Object, Object> INSTANCE = new IsElementOf<Object, Object>(); 046 047 // constructors 048 //--------------------------------------------------------------- 049 /** 050 * Create a new IsElementOf. 051 */ 052 public IsElementOf() { 053 } 054 055 // instance methods 056 //--------------------------------------------------------------- 057 /** 058 * {@inheritDoc} 059 */ 060 public boolean test(L obj, R col) { 061 if (col instanceof Collection<?>) { 062 return testCollection(obj, (Collection<?>) col); 063 } 064 if (null != col && col.getClass().isArray()) { 065 return testArray(obj, col); 066 } 067 if (null == col) { 068 throw new IllegalArgumentException("Right side argument must not be null."); 069 } 070 throw new IllegalArgumentException("Expected Collection or Array, found " + col.getClass()); 071 } 072 073 /** 074 * {@inheritDoc} 075 */ 076 public boolean equals(Object obj) { 077 return (obj instanceof IsElementOf<?, ?>); 078 } 079 080 /** 081 * {@inheritDoc} 082 */ 083 public int hashCode() { 084 return "IsElementOf".hashCode(); 085 } 086 087 /** 088 * {@inheritDoc} 089 */ 090 public String toString() { 091 return "IsElementOf"; 092 } 093 094 /** 095 * Test a collection. 096 * @param obj to find 097 * @param col to search 098 * @return boolean 099 */ 100 private boolean testCollection(Object obj, Collection<?> col) { 101 return col.contains(obj); 102 } 103 104 /** 105 * Test an array. 106 * @param obj to find 107 * @param array to search 108 * @return boolean 109 */ 110 private boolean testArray(Object obj, Object array) { 111 for (int i = 0, m = Array.getLength(array); i < m; i++) { 112 Object value = Array.get(array, i); 113 if (obj == value) { 114 return true; 115 } 116 if (obj != null && obj.equals(value)) { 117 return true; 118 } 119 } 120 return false; 121 } 122 123 // static methods 124 //--------------------------------------------------------------- 125 /** 126 * Get an IsElementOf instance. 127 * @return IsElementOf 128 */ 129 public static IsElementOf<Object, Object> instance() { 130 return INSTANCE; 131 } 132 133 /** 134 * Get an IsElementOf(collection|array) UnaryPredicate. 135 * @param obj collection/array to search 136 * @return UnaryPredicate 137 */ 138 public static <A> UnaryPredicate<A> instance(Object obj) { 139 if (null == obj) { 140 throw new NullPointerException("Argument must not be null"); 141 } else if (obj instanceof Collection<?>) { 142 return new RightBoundPredicate<A>(new IsElementOf<A, Object>(), obj); 143 } else if (obj.getClass().isArray()) { 144 return new RightBoundPredicate<A>(new IsElementOf<A, Object>(), obj); 145 } else { 146 throw new IllegalArgumentException("Expected Collection or Array, found " + obj.getClass()); 147 } 148 } 149 150 }