package pt.utl.ist.fenix.tools.util;

import java.io.Serializable;

import com.linkare.commons.metainfo.Linkare;

/**
 * A pair is simple aggregation of two values. This class can be used to keep two values together, like a key and value, without depending in any particular
 * data structure.
 * 
 * @author <a href="mailto:goncalo@ist.utl.pt">Goncalo Luiz</a> <br/>
 * <br/>
 * <br/>
 *         Created on 13:27:42,31/Mar/2006
 * @version $Id: Pair.java 35158 2008-04-07 15:23:35Z nmgo $
 */
@Linkare(author = "Paulo Zenida", comments = "Changed the class to include the implementations of methods equals() and hashCode()")
public class Pair<K, V> implements Serializable {

    private static final long serialVersionUID = 1L;

    private K key;
    private V value;

    public Pair(K key, V value) {
	this.key = key;
	this.value = value;
    }

    public K getKey() {
	return key;
    }

    public V getValue() {
	return value;
    }

    @Override
    public String toString() {
	return "Pair(" + getKey() + ", " + getValue() + ")";
    }

    @Override
    public boolean equals(Object obj) {
	if (!(obj instanceof Pair)) {
	    return false;
	}
	final Pair other = (Pair) obj;
	return equals(other.getKey(), this.getKey()) && equals(other.getValue(), this.getValue());
    }

    @Override
    public int hashCode() {
	int result = 31;
	result += getKey() == null ? 0 : getKey().hashCode();
	result += getValue() == null ? 0 : getValue().hashCode();
	return result;
    }

    private boolean equals(final Object obj1, final Object obj2) {
	return obj1 == null ? obj2 == null : obj1.equals(obj2);
    }
}