tmf/org.eclipse.tracecompass.tmf.core/src/org/eclipse/tracecompass/tmf/core/util/Pair.java

   1 /*******************************************************************************
   2  * Copyright (c) 2012, 2015 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   Philippe Sawicki (INF4990.A2010@gmail.com)   - Initial API and implementation
  11  *   Mathieu Denis    (mathieu.denis55@gmail.com) - Refactored code
  12  *   Bernd Hufmann - Integrated to TMF, fixed hashCode() and equals() methods
  13  *   Alexandre Montplaisir - Made non-null and immutable
  14  *******************************************************************************/
  15 package org.eclipse.tracecompass.tmf.core.util;
  16
  17 import org.eclipse.jdt.annotation.Nullable;
  18 import org.eclipse.tracecompass.common.core.NonNullUtils;
  19
  20 /**
  21  * Pair utility class, encapsulates a pair of objects.
  22  *
  23  * @param <A>
  24  *            The type of the first object.
  25  * @param <B>
  26  *            The type of the second object.
  27  *
  28  * @author Philippe Sawicki
  29  */
  30 public class Pair<A, B> {
  31
  32     /**
  33      * A reference to the first object.
  34      */
  35     private final A fFirst;
  36     /**
  37      * A reference to the second object.
  38      */
  39     private final B fSecond;
  40
  41     /**
  42      * Constructor.
  43      * @param first
  44      *            The pair's first object.
  45      * @param second
  46      *            The pair's second object.
  47      */
  48     public Pair(A first, B second) {
  49         fFirst = first;
  50         fSecond = second;
  51     }
  52
  53
  54     /**
  55      * Returns a reference to the pair's first object.
  56      *
  57      * @return A reference to the pair's first object.
  58      */
  59     public A getFirst() {
  60         return fFirst;
  61     }
  62
  63     /**
  64      * Returns a reference to the pair's second object.
  65      *
  66      * @return A reference to the pair's second object.
  67      */
  68     public B getSecond() {
  69         return fSecond;
  70     }
  71
  72
  73     @Override
  74     public int hashCode() {
  75         final int prime = 31;
  76         int result = 1;
  77         result = prime * result + hashFromNullable(fFirst);
  78         result = prime * result + hashFromNullable(fSecond);
  79         return result;
  80     }
  81
  82     private static int hashFromNullable(@Nullable Object o) {
  83         return o == null ? 0 : o.hashCode();
  84     }
  85
  86     @Override
  87     public boolean equals(@Nullable Object obj) {
  88         if (this == obj) {
  89             return true;
  90         }
  91         if (obj == null) {
  92             return false;
  93         }
  94         if (getClass() != obj.getClass()) {
  95             return false;
  96         }
  97         Pair<?, ?> other = (Pair<?, ?>) obj;
  98         if (!NonNullUtils.equalsNullable(other.fFirst, fFirst)) {
  99             return false;
 100         }
 101         if (!NonNullUtils.equalsNullable(other.fSecond, fSecond)) {
 102             return false;
 103         }
 104         return true;
 105     }
 106
 107     @Override
 108     public String toString() {
 109         return "(" + fFirst + ", " + fSecond + ")";  //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$
 110     }
 111 }