foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/internal/helper/MappingCompare.java

/*
 * Copyright (c) 1998, 2021 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.internal.helper;

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

import org.eclipse.persistence.mappings.DatabaseMapping;

/**
 * INTERNAL:
 * Use to Sort The mappings in ClassDescriptor, Mappings are either DirectToField, which must be at the top
 * or other
 * Avoid using this class as sun.misc is not part of many VM's like Netscapes.
 *
 */
public class MappingCompare implements Comparator<DatabaseMapping>, Serializable {

    private static final long serialVersionUID = -2749222441763925989L;

    @Override
    public int compare(DatabaseMapping arg1, DatabaseMapping arg2) {
        int arg1Value = arg1.getWeight();
        int arg2Value = arg2.getWeight();
        if (arg1Value == arg2Value) {
            int result = arg1.getClass().getName().compareTo(arg2.getClass().getName());
            // For same classes, compare attribute names.
            if (result == 0) {
                // Can be null for TransformationMapping.
                if (arg1.getAttributeName() != null && arg2.getAttributeName() != null) {
                    result = arg1.getAttributeName().compareTo(arg2.getAttributeName());
                }
            }
            return result;
        }
        return (arg1Value - arg2Value);
    }
}