GenericEntityIdComparator.java

package fr.openwide.core.jpa.business.generic.util;

import java.io.Serializable;
import java.util.Comparator;

import fr.openwide.core.jpa.business.generic.model.GenericEntity;

/**
 * This is a default comparator, it should probably not be used in production.
 * 
 * Inherit from {@link AbstractGenericEntityComparator} instead.
 */
public class GenericEntityIdComparator implements Comparator<GenericEntity<Long, ?>>, Serializable {
	
	private static final long serialVersionUID = -9178542049081510289L;

	private static final GenericEntityIdComparator INSTANCE = new GenericEntityIdComparator();
	
	public static final GenericEntityIdComparator get() {
		return INSTANCE;
	}

	@Override
	public int compare(GenericEntity<Long, ?> o1, GenericEntity<Long, ?> o2) {
		if (o1.getId() != null && o2.getId() != null) {
			return o1.getId().compareTo(o2.getId());
		} else if (o1.getId() != null && o2.getId() == null) {
			// les éléments les plus récents sont les plus élevés pour le comparateur
			return -1;
		} else if (o1.getId() == null && o2.getId() != null) {
			return 1;
		}
		return 0;
	}
	
	private GenericEntityIdComparator() {
	}

}