// FitnessAndCrowdingDistanceComparator.java
//
// Author:
// Antonio J. Nebro <antonio@lcc.uma.es>
// Juan J. Durillo <durillo@lcc.uma.es>
//
// Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
// This program 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 of the License, or
// (at your option) any later version.
//
// This program 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 program. If not, see <http://www.gnu.org/licenses/>.
package jmetal.util.comparators;
import java.util.Comparator;
/**
* This class implements a <code>Comparator</code> (a method for comparing
* <code>Solution</code> objects) based on the fitness and crowding distance.
*/
public class FitnessAndCrowdingDistanceComparator implements Comparator{
/**
* stores a comparator for check the fitness value of the solutions
*/
private static final Comparator fitnessComparator_ =
new FitnessComparator();
/**
* stores a comparator for check the crowding distance
*/
private static final Comparator crowdingDistanceComparator_ =
new CrowdingDistanceComparator();
/**
* Compares two solutions.
* @param solution1 Object representing the first <code>Solution</code>.
* @param solution2 Object representing the second <code>Solution</code>.
* @return -1, or 0, or 1 if solution1 is less than, equal, or greater than
* solution2, respectively.
*/
public int compare(Object solution1, Object solution2) {
int flag = fitnessComparator_.compare(solution1,solution2);
if (flag != 0) {
return flag;
} else {
return crowdingDistanceComparator_.compare(solution1,solution2);
}
} // compares
} // FitnessAndCrowdingDistanceComparator