Pair.java

/**
 * Copyright (C) 2007 Google Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library 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
 * Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

package org.makersoft.shards.utils;

/**
 * A simple class to represent a pair.
 * 
 * @author maxr@google.com (Max Ross)
 */
public class Pair<A, B> {
	public final A first;

	/** The second element of the pair. */
	public final B second;

	private Pair(/* @Nullable */A first, /* @Nullable */B second) {
		this.first = first;
		this.second = second;
	}

	public A getFirst() {
		return first;
	}

	public B getSecond() {
		return second;
	}

	public static <A, B> Pair<A, B> of(/* @Nullable */A first, /* @Nullable */
			B second) {
		return new Pair<A, B>(first, second);
	}

	private static boolean eq(/* @Nullable */Object a, /* @Nullable */Object b) {
		return a == b || (a != null && a.equals(b));
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((first == null) ? 0 : first.hashCode());
		result = prime * result + ((second == null) ? 0 : second.hashCode());
		return result;
	}

	@Override
	public boolean equals(/* @Nullable */Object object) {
		if (object instanceof Pair<?, ?>) {
			Pair<?, ?> other = (Pair<?, ?>) object;
			return eq(first, other.first) && eq(second, other.second);
		}
		return false;
	}
}