asc.java

Mandarax是一个规则引擎的纯Java实现。它支持多类型的事实和基于反映的规则

package org.mandarax.util.resultsetfilters;

/*
 * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
 *
 * 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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
 
import org.mandarax.kernel.VariableTerm;

/**
 * Order by condition for sorting in ascending order.
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 3.0
 */

public class ASC implements OrderByCondition {
	private VariableTerm var = null;
	/**
	 * Constructor.
 	 * @param var the variable that is to be sorted
	 */
	public ASC (VariableTerm variable) {
		super();
		var = variable;
	}
	/**
	 * Compare two objects.
	 * @param obj1 object 1
	 * @param obj2 object 2
	 * @return a number
	 * @see java.util.Comparator
	 */
	public int compareTo(Object obj1,Object obj2) throws OrderByException {
		if (obj1==null || obj2==null) throw new OrderByException("Cannot compare with null");
		if (!(obj1 instanceof Comparable)) throw new OrderByException("Cannot sort this object, it does not implement Comparable: " + obj1);
		if (!(obj2 instanceof Comparable)) throw new OrderByException("Cannot sort this object, it does not implement Comparable: " + obj2);
		return ((Comparable)obj1).compareTo(obj2);
	}
	/**
	 * Get the variable term.
	 * @return a variable term
	 */
	public VariableTerm getVariable() {
		return var;
	}
}