1 /**
2 *
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 */
19
20 package org.apache.hadoop.hbase.util;
21
22 import java.io.Serializable;
23
24 import org.apache.hadoop.hbase.classification.InterfaceAudience;
25 import org.apache.hadoop.hbase.classification.InterfaceStability;
26
27 /**
28 * A generic class for pairs.
29 * @param <T1>
30 * @param <T2>
31 */
32 @InterfaceAudience.Public
33 @InterfaceStability.Stable
34 public class Pair<T1, T2> implements Serializable
35 {
36 private static final long serialVersionUID = -3986244606585552569L;
37 protected T1 first = null;
38 protected T2 second = null;
39
40 /**
41 * Default constructor.
42 */
43 public Pair()
44 {
45 }
46
47 /**
48 * Constructor
49 * @param a operand
50 * @param b operand
51 */
52 public Pair(T1 a, T2 b)
53 {
54 this.first = a;
55 this.second = b;
56 }
57
58 /**
59 * Constructs a new pair, inferring the type via the passed arguments
60 * @param <T1> type for first
61 * @param <T2> type for second
62 * @param a first element
63 * @param b second element
64 * @return a new pair containing the passed arguments
65 */
66 public static <T1,T2> Pair<T1,T2> newPair(T1 a, T2 b) {
67 return new Pair<T1,T2>(a, b);
68 }
69
70 /**
71 * Replace the first element of the pair.
72 * @param a operand
73 */
74 public void setFirst(T1 a)
75 {
76 this.first = a;
77 }
78
79 /**
80 * Replace the second element of the pair.
81 * @param b operand
82 */
83 public void setSecond(T2 b)
84 {
85 this.second = b;
86 }
87
88 /**
89 * Return the first element stored in the pair.
90 * @return T1
91 */
92 public T1 getFirst()
93 {
94 return first;
95 }
96
97 /**
98 * Return the second element stored in the pair.
99 * @return T2
100 */
101 public T2 getSecond()
102 {
103 return second;
104 }
105
106 private static boolean equals(Object x, Object y)
107 {
108 return (x == null && y == null) || (x != null && x.equals(y));
109 }
110
111 @Override
112 @SuppressWarnings("unchecked")
113 public boolean equals(Object other)
114 {
115 return other instanceof Pair && equals(first, ((Pair)other).first) &&
116 equals(second, ((Pair)other).second);
117 }
118
119 @Override
120 public int hashCode()
121 {
122 if (first == null)
123 return (second == null) ? 0 : second.hashCode() + 1;
124 else if (second == null)
125 return first.hashCode() + 2;
126 else
127 return first.hashCode() * 17 + second.hashCode();
128 }
129
130 @Override
131 public String toString()
132 {
133 return "{" + getFirst() + "," + getSecond() + "}";
134 }
135 }