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Contains common classes of projects, which allow to parse feeds
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/*
 * JavaFeedParserCommon Copyright 2013-2014 Michael Rapp
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see . 
 */
package de.mrapp.parser.feed.common.datastructure;

import static de.mrapp.parser.feed.common.util.Condition.ensureNotNull;

import java.io.Serializable;

/**
 * A data structure, which contains a pair of values of any generic type, which
 * is extended from the interface {@link Serializable}.
 * 
 * 
 * @param 
 *            The type of the first value
 * @param 
 *            The type of the second value
 * 
 * @author Michael Rapp
 * 
 * @since 1.0.0
 */
public class Pair
		implements Serializable {

	/**
	 * The constant serial version UID.
	 */
	private static final long serialVersionUID = 1L;

	/**
	 * The first value.
	 */
	private FirstType first;

	/**
	 * The seconds value.
	 */
	private SecondType second;

	/**
	 * Creates a new data structure, which contains a pair of values.
	 * 
	 * @param first
	 *            The first value. The value may not be null
	 * @param second
	 *            The second value. The value may not be null
	 */
	public Pair(final FirstType first, final SecondType second) {
		setFirst(first);
		setSecond(second);
	}

	/**
	 * Returns the first value.
	 * 
	 * @return The first value as an instance of the type FirstType. The value
	 *         may not be null
	 */
	public final FirstType getFirst() {
		return first;
	}

	/**
	 * Sets the first value.
	 * 
	 * @param first
	 *            The value, which should be set, as an instance of the type
	 *            FirstType. The value may not be null
	 */
	public final void setFirst(final FirstType first) {
		ensureNotNull(first, "The value may not be null");
		this.first = first;
	}

	/**
	 * Returns the second value.
	 * 
	 * @return The second value as an instance of the type SecondType. The value
	 *         may not be null
	 */
	public final SecondType getSecond() {
		return second;
	}

	/**
	 * Sets the second value.
	 * 
	 * @param second
	 *            The value, which should be set, as an instance of the type
	 *            SecondType. The value may not be null
	 */
	public final void setSecond(final SecondType second) {
		ensureNotNull(second, "The value may not be null");
		this.second = second;
	}

	/**
	 * Creates and returns a new data structure, which contains a pair of
	 * values.
	 * 
	 * @param 
	 *            The type of the first value
	 * @param 
	 *            The type of the second value
	 * @param first
	 *            The first value. The value may not be null
	 * @param second
	 *            The second value. The value may not be null
	 * @return The pair of values, which has been created
	 */
	public static  Pair create(
			final FirstType first, final SecondType second) {
		return new Pair(first, second);
	}

	@Override
	public final String toString() {
		return "Pair [first=" + first + ", second=" + second + "]";
	}

	@Override
	public final int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + first.hashCode();
		result = prime * result + second.hashCode();
		return result;
	}

	@Override
	public final boolean equals(final Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Pair other = (Pair) obj;
		if (!first.equals(other.first))
			return false;
		if (!second.equals(other.second))
			return false;
		return true;
	}

}