FeatureSorter.java example

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/*
 * This file is part of JGrasstools (http://www.jgrasstools.org)
 * (C) HydroloGIS - www.hydrologis.com 
 * 
 * JGrasstools is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.jgrasstools.gears.utils.features;

import java.util.Comparator;
import java.util.List;

import org.opengis.feature.simple.SimpleFeature;

/**
 * Sorts a {@link List} of features by one of the fields.
 * 
 * @author Andrea Antonello (www.hydrologis.com)
 */
public class FeatureSorter implements Comparator<SimpleFeature> {
    private final String fieldName;

    public FeatureSorter( String fieldName ) {
        this.fieldName = fieldName;
    }

    public int compare( SimpleFeature f1, SimpleFeature f2 ) {
        if (fieldName == null) {
            throw new IllegalArgumentException("A fieldname for the sorting has to be defined.");
        }

        Object a1 = f1.getAttribute(fieldName);
        Object a2 = f2.getAttribute(fieldName);

        if (a1 instanceof Number && a2 instanceof Number) {
            double d1 = ((Number) a1).doubleValue();
            double d2 = ((Number) a2).doubleValue();
            if (d1 < d2) {
                return -1;
            } else if (d1 > d2) {
                return 1;
            } else {
                return 0;
            }
        }
        throw new IllegalArgumentException("Type not supported.");
    }

}