CreationTimeComparator.java

/*
 * Copyright (c) 2015 EMC Corporation
 * All Rights Reserved
 */
package com.emc.sa.model.util;

import java.util.Comparator;

import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.comparators.ComparatorChain;
import org.apache.commons.collections.comparators.NullComparator;

import com.emc.storageos.db.client.model.DataObject;

public class CreationTimeComparator implements Comparator<DataObject> {

    private static final String CREATION_TIME = "creationTime";

    private ComparatorChain COMPARATOR;

    private boolean reverseOrder = false;

    public CreationTimeComparator() {

    }

    public CreationTimeComparator(boolean reverseOrder) {
        this.reverseOrder = reverseOrder;
    }

    @Override
    public int compare(DataObject o1, DataObject o2) {
        return getComparator().compare(o1, o2);
    }

    private ComparatorChain getComparator() {
        if (COMPARATOR == null) {
            COMPARATOR = new ComparatorChain();
            COMPARATOR.addComparator(new BeanComparator(CREATION_TIME, new NullComparator()), reverseOrder);
        }
        return COMPARATOR;
    }

    public static final CreationTimeComparator NEWEST_FIRST = new CreationTimeComparator(true);
    public static final CreationTimeComparator OLDEST_FIRST = new CreationTimeComparator();
}