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

/*
 * Copyright (c) 1998, 2019 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:
//     06/10/2009 Andrei Ilitchev
//       - JPA 2.0 - OrderedList support.
package org.eclipse.persistence.internal.helper;

import java.util.Collections;
import java.util.Comparator;

import org.eclipse.persistence.internal.queries.OrderedListContainerPolicy;

/**
 * <p><b>Purpose</b>: A helper class for sorting index/object pairs.
 * <p><b>Responsibilities</b>:
 * Allows to sort a list of index/object pairs either directly
 * or with {@code Collections.sort(List<IndexedObject>)} - using {@code IndexedObject.compareTo};
 * or with {@code Collections.sort(List<IndexedObject>, Comparator<IndexedObject>)} - using custom-defined {@code Comparator<IndexedObject>}.
 *
 * @see Collections
 * @see Comparator
 * @see OrderedListContainerPolicy
 */
public class IndexedObject implements Comparable<IndexedObject> {
    private Integer index;
    private Object object;
    public IndexedObject(Integer index, Object object) {
        this.index = index;
        this.object = object;
    }

    public Integer getIndex() {
        return index;
    }

    public void setIndex(Integer index) {
        this.index = index;
    }

    public Object getObject() {
        return object;
    }

    public void setObject(Object object) {
        this.object = object;
    }

    /*
     * Compares indexes, null is less than any non-null.
     */
    @Override
    public int compareTo(IndexedObject anotherIndexedObject) {
        Integer anotherIndex = anotherIndexedObject.getIndex();
        if(index == null) {
            if(anotherIndex == null) {
                return 0;
            } else {
                return -1;
            }
        } else {
            if(anotherIndex == null) {
                return 1;
            } else {
                return index.compareTo(anotherIndex);
            }
        }
    }

    @Override
    public String toString() {
        return "(" + index + ", " + object + ")";
    }
}