Pair.java revision d4a1d2e14297a3387fdb5761090961e714370492
1d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana/* 2d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Copyright (C) 2009 The Android Open Source Project 3d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * 4d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Licensed under the Apache License, Version 2.0 (the "License"); 5d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * you may not use this file except in compliance with the License. 6d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * You may obtain a copy of the License at 7d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * 8d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * http://www.apache.org/licenses/LICENSE-2.0 9d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * 10d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Unless required by applicable law or agreed to in writing, software 11d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * distributed under the License is distributed on an "AS IS" BASIS, 12d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * See the License for the specific language governing permissions and 14d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * limitations under the License. 15d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana */ 16d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana 17d4a1d2e14297a3387fdb5761090961e714370492Fred Quintanapackage android.util; 18d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana 19d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana/** 20d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Container to ease passing around a tuple of two objects. This object provides a sensible 21d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * implementation of equals(), returning true if equals() is true on each of the contained 22d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * objects. 23d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana */ 24d4a1d2e14297a3387fdb5761090961e714370492Fred Quintanapublic class Pair<F, S> { 25d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana public final F first; 26d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana public final S second; 27d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana 28d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana /** 29d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Constructor for a Pair. If either are null then equals() and hashCode() will throw 30d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * a NullPointerException. 31d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @param first the first object in the Pair 32d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @param second the second object in the pair 33d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana */ 34d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana public Pair(F first, S second) { 35d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana this.first = first; 36d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana this.second = second; 37d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana } 38d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana 39d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana /** 40d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Checks the two objects for equality by delegating to their respective equals() methods. 41d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @param o the Pair to which this one is to be checked for equality 42d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @return true if the underlying objects of the Pair are both considered equals() 43d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana */ 44d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana public boolean equals(Object o) { 45d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana if (o == this) return true; 46d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana if (!(o instanceof Pair)) return false; 47d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana final Pair<F, S> other; 48d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana try { 49d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana other = (Pair<F, S>) o; 50d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana } catch (ClassCastException e) { 51d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana return false; 52d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana } 53d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana return first.equals(other.first) && second.equals(other.second); 54d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana } 55d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana 56d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana /** 57d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Compute a hash code using the hash codes of the underlying objects 58d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @return a hashcode of the Pair 59d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana */ 60d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana public int hashCode() { 61d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana int result = 17; 62d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana result = 31 * result + first.hashCode(); 63d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana result = 31 * result + second.hashCode(); 64d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana return result; 65d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana } 66d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana 67d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana /** 68d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * Convenience method for creating an appropriately typed pair. 69d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @param a the first object in the Pair 70d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @param b the second object in the pair 71d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana * @return a Pair that is templatized with the types of a and b 72d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana */ 73d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana public static <A, B> Pair <A, B> create(A a, B b) { 74d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana return new Pair<A, B>(a, b); 75d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana } 76d4a1d2e14297a3387fdb5761090961e714370492Fred Quintana} 77