ar.com.zauber.commons.dao.Ordering.java Source code

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/**
 * Copyright (c) 2005-2012 Zauber S.A. <http://www.zaubersoftware.com/>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package ar.com.zauber.commons.dao;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.apache.commons.lang.Validate;

/**
 * Representa un orden. Est compuesto  por un listado de <code>Order</code>
 * con el fin de definir en cada caso cual es la propiedad y si es ascendente
 * o descendente.
 * 
 * 
 * @author Martin A. Marquez
 * @since Sep 24, 2007
 */
public class Ordering {
    private final List<Order> orders;

    /** creates an empty ordering */
    @SuppressWarnings("unchecked")
    public Ordering() {
        this(Collections.EMPTY_LIST);
    }

    /** @param orders orders */
    public Ordering(final Order... orders) {
        this(Arrays.asList(orders));
    }

    /** @param orders orders*/
    public Ordering(final List<Order> orders) {
        Validate.noNullElements(orders);
        this.orders = orders;
    }

    /** return the orders. the returned list can't be modified */
    public final List<Order> getOrders() {
        return Collections.unmodifiableList(orders);
    }

    /** @see Object#toString() */
    @Override
    public final String toString() {
        return "ORDER BY " + orders.toString();
    }

    /** @see Object#equals(Object) */
    @Override
    public final boolean equals(final Object obj) {
        boolean ret = false;

        if (obj == this) {
            ret = true;
        } else if (obj instanceof Ordering) {
            final Ordering ordering = (Ordering) obj;
            ret = orders.equals(ordering.orders);
        }
        return ret;
    }

    /** @see Object#hashCode() */
    @Override
    public final int hashCode() {
        return 37 + 17 * 37 + orders.hashCode();
    }

    /**
     *  return a  {@link OrderingBuilder} that ease the  creation. Ej:
     *  <verbatim>
     *  final Ordering expected = new Ordering(
     *          new Order("name"), 
     *          new Order("username", true, true),
     *          new Order("points", false), 
     *          new Order("foo", false, true));
     *   </verbatim> 
     * 
     * */
    public static OrderingBuilder builder() {
        return new OrderingBuilder();
    }
}