1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 package org.chromium.mojo.system;
6 
7 
8 /**
9  * A pair of object.
10  *
11  * @param <F> Type of the first element.
12  * @param <S> Type of the second element.
13  */
14 public class Pair<F, S> {
15 
16     public final F first;
17     public final S second;
18 
19     /**
20      * Dedicated constructor.
21      *
22      * @param first the first element of the pair.
23      * @param second the second element of the pair.
24      */
Pair(F first, S second)25     public Pair(F first, S second) {
26         this.first = first;
27         this.second = second;
28     }
29 
30     /**
31      * equals() that handles null values.
32      */
equals(Object o1, Object o2)33     private boolean equals(Object o1, Object o2) {
34         return o1 == null ? o2 == null : o1.equals(o2);
35     }
36 
37     /**
38      * @see Object#equals(Object)
39      */
40     @Override
equals(Object o)41     public boolean equals(Object o) {
42         if (!(o instanceof Pair)) {
43             return false;
44         }
45         Pair<?, ?> p = (Pair<?, ?>) o;
46         return equals(first, p.first) && equals(second, p.second);
47     }
48 
49     /**
50      * @see Object#hashCode()
51      */
52     @Override
hashCode()53     public int hashCode() {
54         return (first == null ? 0 : first.hashCode()) ^ (second == null ? 0 : second.hashCode());
55     }
56 
57     /**
58      * Helper method for creating a pair.
59      *
60      * @param a the first element of the pair.
61      * @param b the second element of the pair.
62      * @return the pair containing a and b.
63      */
create(A a, B b)64     public static <A, B> Pair<A, B> create(A a, B b) {
65         return new Pair<A, B>(a, b);
66     }
67 }
68