https://github.com/eclipse/eclipse-collections/eclipse-collections-api: Eclipse Collections is a collections framework for Java. It has JDK-compatible List, Set and Map implementations with a rich API and set of utility classes that work with any JDK compatible Collections, Arrays, Maps or Strings. The iteration protocol was inspired by the Smalltalk collection framework.
  • Craig P. Motlin
  • Donald Raab
  • Mohammad A. Rezaei
  • Hiroshi Ito
  • Nikhil J. Nanivadekar
  • Sirisha Pratha 
/*
 * Copyright (c) 2021 Goldman Sachs and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompany this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */

package org.eclipse.collections.api.tuple;

import java.io.Serializable;
import java.util.Map;
import java.util.Objects;


A Pair is a container that holds two related objects. It is the equivalent of an Association in Smalltalk, or an
implementation of Map.Entry in the JDK.
An instance of this interface can be created by calling Tuples.pair(Object, Object) or Tuples.twin(Object, Object).

/**
 * A Pair is a container that holds two related objects. It is the equivalent of an Association in Smalltalk, or an
 * implementation of Map.Entry in the JDK.
 *
 * An instance of this interface can be created by calling Tuples.pair(Object, Object) or Tuples.twin(Object, Object).
 */
public interface Pair<T1, T2>
        extends Serializable, Comparable<Pair<T1, T2>>
{
    T1 getOne();

    T2 getTwo();

    void put(Map<? super T1, ? super T2> map);

    Map.Entry<T1, T2> toEntry();

    
Method used to swap the elements of pair.

e.g.
Pair<String, Integer> pair = Tuples.pair("One", 1);
Pair<Integer, String> swappedPair = pair.swap();



Since:6.0
/**
     * Method used to swap the elements of pair.
     *
     * <pre>e.g.
     * Pair&lt;String, Integer&gt; pair = Tuples.pair("One", 1);
     * Pair&lt;Integer, String&gt; swappedPair = pair.swap();
     * </pre>
     *
     * @since 6.0
     */
    Pair<T2, T1> swap();

    /*
     * Returns true if value of getOne() is equal to value of getTwo().
     *
     * @since 11.0
     */
    default boolean isEqual()
    {
        return Objects.equals(this.getOne(), this.getTwo());
    }

    /*
     * Returns true if value of getOne() is the same instance as the value of getTwo().
     *
     * @since 11.0
     */
    default boolean isSame()
    {
        return this.getOne() == this.getTwo();
    }
}