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