1 /**
2 * Copyright 2010 The Apache Software Foundation
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20
21 package org.apache.hadoop.hbase.util;
22
23 import java.io.Serializable;
24
25 /**
26 * A generic class for pairs.
27 * @param <T1>
28 * @param <T2>
29 */
30 public class Pair<T1, T2> implements Serializable
31 {
32 private static final long serialVersionUID = -3986244606585552569L;
33 protected T1 first = null;
34 protected T2 second = null;
35
36 /**
37 * Default constructor.
38 */
39 public Pair()
40 {
41 }
42
43 /**
44 * Constructor
45 * @param a operand
46 * @param b operand
47 */
48 public Pair(T1 a, T2 b)
49 {
50 this.first = a;
51 this.second = b;
52 }
53
54 /**
55 * Constructs a new pair, inferring the type via the passed arguments
56 * @param <T1> type for first
57 * @param <T2> type for second
58 * @param a first element
59 * @param b second element
60 * @return a new pair containing the passed arguments
61 */
62 public static <T1,T2> Pair<T1,T2> newPair(T1 a, T2 b) {
63 return new Pair<T1,T2>(a, b);
64 }
65
66 /**
67 * Replace the first element of the pair.
68 * @param a operand
69 */
70 public void setFirst(T1 a)
71 {
72 this.first = a;
73 }
74
75 /**
76 * Replace the second element of the pair.
77 * @param b operand
78 */
79 public void setSecond(T2 b)
80 {
81 this.second = b;
82 }
83
84 /**
85 * Return the first element stored in the pair.
86 * @return T1
87 */
88 public T1 getFirst()
89 {
90 return first;
91 }
92
93 /**
94 * Return the second element stored in the pair.
95 * @return T2
96 */
97 public T2 getSecond()
98 {
99 return second;
100 }
101
102 private static boolean equals(Object x, Object y)
103 {
104 return (x == null && y == null) || (x != null && x.equals(y));
105 }
106
107 @Override
108 @SuppressWarnings("unchecked")
109 public boolean equals(Object other)
110 {
111 return other instanceof Pair && equals(first, ((Pair)other).first) &&
112 equals(second, ((Pair)other).second);
113 }
114
115 @Override
116 public int hashCode()
117 {
118 if (first == null)
119 return (second == null) ? 0 : second.hashCode() + 1;
120 else if (second == null)
121 return first.hashCode() + 2;
122 else
123 return first.hashCode() * 17 + second.hashCode();
124 }
125
126 @Override
127 public String toString()
128 {
129 return "{" + getFirst() + "," + getSecond() + "}";
130 }
131 }