/**
*
* This file is part of EvoSuite.
*
* EvoSuite 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 3.0 of the License, or
* (at your option) any later version.
*
* EvoSuite 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 Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
*/
package org.evosuite.ga.metaheuristics.mosa.comparators;
import java.util.Comparator;
import org.evosuite.ga.Chromosome;
/**
* This class implements a <code>Comparator</code> (a method for comparing <code>Chromosomes</code>
* objects) based on the dominance test, as in NSGA-II.
*
* @author Annibale Panichella
*/
public class RankAndCrowdingDistanceComparator<T extends Chromosome> implements Comparator<Object> {
/**
* Constructor
*
* @param comparator
*/
public RankAndCrowdingDistanceComparator() {
}
/**
* Compares two solutions.
*
* @param object1
* Object representing the first <code>Solution</code>.
* @param object2
* Object representing the second <code>Solution</code>.
* @return -1, or 0, or 1 according to the non-dominated ranks
*/
@SuppressWarnings("unchecked")
public int compare(Object object1, Object object2) {
if (object1 == null)
return 1;
else if (object2 == null)
return -1;
T solution1 = (T) object1;
T solution2 = (T) object2;
if (solution1.getRank()<solution2.getRank())
return -1;
else if (solution1.getRank()>solution2.getRank())
return +1;
else if (solution1.getDistance()>solution2.getDistance())
return -1;
else if (solution2.getDistance()>solution1.getDistance())
return +1;
return 0;
} // compare
} // DominanceComparator