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 import java.util.Objects; 20 21 /** 22 * Container to ease passing around a tuple of two objects. This object provides a sensible 23 * implementation of equals(), returning true if equals() is true on each of the contained 24 * objects. 25 */ 26 public class Pair<F, S> { 27 public final F first; 28 public final S second; 29 30 /** 31 * Constructor for a Pair. 32 * 33 * @param first the first object in the Pair 34 * @param second the second object in the pair 35 */ 36 public Pair(F first, S second) { 37 this.first = first; 38 this.second = second; 39 } 40 41 /** 42 * Checks the two objects for equality by delegating to their respective 43 * {@link Object#equals(Object)} methods. 44 * 45 * @param o the {@link Pair} to which this one is to be checked for equality 46 * @return true if the underlying objects of the Pair are both considered 47 * equal 48 */ 49 @Override 50 public boolean equals(Object o) { 51 if (!(o instanceof Pair)) { 52 return false; 53 } 54 Pair<?, ?> p = (Pair<?, ?>) o; 55 return Objects.equals(p.first, first) && Objects.equals(p.second, second); 56 } 57 58 /** 59 * Compute a hash code using the hash codes of the underlying objects 60 * 61 * @return a hashcode of the Pair 62 */ 63 @Override 64 public int hashCode() { 65 return (first == null ? 0 : first.hashCode()) ^ (second == null ? 0 : second.hashCode()); 66 } 67 68 @Override 69 public String toString() { 70 return "Pair{" + String.valueOf(first) + " " + String.valueOf(second) + "}"; 71 } 72 73 /** 74 * Convenience method for creating an appropriately typed pair. 75 * @param a the first object in the Pair 76 * @param b the second object in the pair 77 * @return a Pair that is templatized with the types of a and b 78 */ 79 public static <A, B> Pair <A, B> create(A a, B b) { 80 return new Pair<A, B>(a, b); 81 } 82 } 83
