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DHIS 2 API client for Java.
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/*
 * Copyright (c) 2004-2024, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of the HISP project nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.util;

import lombok.AccessLevel;
import lombok.NoArgsConstructor;

/** Generic utility class for null-safe comparison. */
@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class Comparing {
  /**
   * Compares two objects for order. Returns a negative integer, zero, or a positive integer if the
   * first object is less than, equal to, or greater than the second object. Any of the objects can
   * be null. A null value is considered to be less than a non-null value.
   *
   * @param  the type.
   * @param a the first object.
   * @param b the second object.
   * @return an integer value.
   */
  public static > int compareTo(T a, T b) {
    if (a == b) {
      return 0;
    }

    return a != null ? b != null ? a.compareTo(b) : 1 : -1;
  }

  /**
   * Compares two objects for order. Returns a negative integer, zero, or a positive integer if the
   * first object is less than, equal to, or greater than the second object. Any of the objects can
   * be null. A null value is considered to be greater than a non-null value.
   *
   * @param  the type.
   * @param a the first object.
   * @param b the second object.
   * @return an integer value.
   */
  public static > int compareToNullLast(T a, T b) {
    if (a == b) {
      return 0;
    }

    return a != null ? b != null ? a.compareTo(b) : -1 : 1;
  }
}