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/*--------------------------------------------------------------------------
 *  Copyright 2004 Taro L. Saito
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *--------------------------------------------------------------------------*/
//--------------------------------------
// XerialJ
//
// Pair.java
// Since: 2004/12/27
//
// $URL$ 
// $Author$
//--------------------------------------
package org.xerial.util;

/**
 * Pair of two objects
 * 
 * @author leo
 * 
 */
public class Pair {
    private final X first;
    private final Y second;

    /**
     * 
     */
    public Pair(X x, Y y) {
        if (x == null || y == null)
            throw new NullPointerException();

        this.first = x;
        this.second = y;
    }

    public X getFirst() {
        return first;
    }

    public Y getSecond() {
        return second;
    }

    public static  Pair newPair(X x, Y y) {
        return new Pair(x, y);
    }

    @Override
    public String toString() {
        return String.format("(%s, %s)", first, second);
    }

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

    @Override
    public int hashCode() {
        return (first.hashCode() * 127 + second.hashCode() * 127) % 1987;
    }
}