hbase-common/src/main/java/org/apache/hadoop/hbase/util/Pair.java

   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.yetus.audience.InterfaceAudience;
  25
  26 /**
  27  * A generic class for pairs.
  28  * @param <T1>
  29  * @param <T2>
  30  */
  31 @InterfaceAudience.Public
  32 public class Pair<T1, T2> implements Serializable
  33 {
  34   private static final long serialVersionUID = -3986244606585552569L;
  35   protected T1 first = null;
  36   protected T2 second = null;
  37
  38   /**
  39    * Default constructor.
  40    */
  41   public Pair()
  42   {
  43   }
  44
  45   /**
  46    * Constructor
  47    * @param a operand
  48    * @param b operand
  49    */
  50   public Pair(T1 a, T2 b)
  51   {
  52     this.first = a;
  53     this.second = b;
  54   }
  55
  56   /**
  57    * Constructs a new pair, inferring the type via the passed arguments
  58    * @param <T1> type for first
  59    * @param <T2> type for second
  60    * @param a first element
  61    * @param b second element
  62    * @return a new pair containing the passed arguments
  63    */
  64   public static <T1,T2> Pair<T1,T2> newPair(T1 a, T2 b) {
  65     return new Pair<>(a, b);
  66   }
  67
  68   /**
  69    * Replace the first element of the pair.
  70    * @param a operand
  71    */
  72   public void setFirst(T1 a)
  73   {
  74     this.first = a;
  75   }
  76
  77   /**
  78    * Replace the second element of the pair.
  79    * @param b operand
  80    */
  81   public void setSecond(T2 b)
  82   {
  83     this.second = b;
  84   }
  85
  86   /**
  87    * Return the first element stored in the pair.
  88    * @return T1
  89    */
  90   public T1 getFirst()
  91   {
  92     return first;
  93   }
  94
  95   /**
  96    * Return the second element stored in the pair.
  97    * @return T2
  98    */
  99   public T2 getSecond()
 100   {
 101     return second;
 102   }
 103
 104   private static boolean equals(Object x, Object y)
 105   {
 106     return (x == null && y == null) || (x != null && x.equals(y));
 107   }
 108
 109   @Override
 110   @SuppressWarnings("unchecked")
 111   public boolean equals(Object other)
 112   {
 113     return other instanceof Pair && equals(first, ((Pair)other).first) &&
 114       equals(second, ((Pair)other).second);
 115   }
 116
 117   @Override
 118   public int hashCode()
 119   {
 120     if (first == null)
 121       return (second == null) ? 0 : second.hashCode() + 1;
 122     else if (second == null)
 123       return first.hashCode() + 2;
 124     else
 125       return first.hashCode() * 17 + second.hashCode();
 126   }
 127
 128   @Override
 129   public String toString()
 130   {
 131     return "{" + getFirst() + "," + getSecond() + "}";
 132   }
 133 }