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Objectos Lang provides utilities for classes in the java.lang package.
There is a newer version: 0.8.0
/*
 * Copyright (C) 2022-2023 Objectos Software LTDA.
 *
 * 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 objectos.lang;

/**
 * Provides {@code static} convenience methods for implementing
 * {@link Object#equals(Object)} methods.
 *
 * @since 0.2
 */
public final class Equals {

  private Equals() {}

  /**
   * Checks if two objects are equal to each other in a null-safe manner.
   *
   * 
   * Returns:
   *
   * 

   * {@code true} if {@code a} is null and {@code b} is null;
   * {@code true} if {@code a} is not null and {@code a.equals(b)} evaluates
   * to {@code true}; and
   * {@code false} otherwise
   * 
   *
   * @param a
   *        the first reference to check for equality
   * @param b
   *        the second reference to check for equality
   *
   * @return {@code true} if the arguments are equal to each other and
   *         {@code false} otherwise
   */
  public static boolean of(Object a, Object b) {
    if (a == b) {
      return true;
    }

    if (a != null) {
      return a.equals(b);
    }

    return false;
  }

  /**
   * Checks if objects are equal to each other in pairs. It checks, in a
   * null-safe manner, if {@code a.equals(b) && c.equals(d)}.
   *
   * 
   * An invocation of this method of the form
   *
   * 
{@code Equals.of(a, b, c, d)}
   *
   * 
   * behaves in exactly the same way as the expression
   *
   * 
{@code Equals.of(a, b) && Equals.of(c, d)}
   *
   * 
   * meaning that if the equality test fails for the first pair, the second pair
   * is not checked.
   *
   * @param a
   *        the first reference of the first pair to check for equality
   * @param b
   *        the second reference of the first pair to check for equality
   * @param c
   *        the first reference of the second pair to check for equality
   * @param d
   *        the second reference of the second pair to check for equality
   *
   * @return {@code true} if
   *         {@code Equals.of(a, b) && Equals.of(c, d)}
   */
  public static boolean of(
      Object a, Object b,
      Object c, Object d) {
    return of(a, b)
        && of(c, d);
  }

  /**
   * Checks if objects are equal to each other in pairs. It checks, in a
   * null-safe manner, if {@code a.equals(b) && c.equals(d) && e.equals(f)}.
   *
   * 

   * An invocation of this method of the form
   *
   * 
{@code Equals.of(a, b, c, d, e, f)}
   *
   * 
   * behaves in exactly the same way as the expression
   *
   * 
{@code Equals.of(a, b) && Equals.of(c, d) &&  Equals.of(e, f)}
   *
   * 
   * meaning that if the equality test fails for the first pair, the second pair
   * is not checked.
   *
   * @param a
   *        the first reference of the first pair to check for equality
   * @param b
   *        the second reference of the first pair to check for equality
   * @param c
   *        the first reference of the second pair to check for equality
   * @param d
   *        the second reference of the second pair to check for equality
   * @param e
   *        the first reference of the third pair to check for equality
   * @param f
   *        the second reference of the third pair to check for equality
   *
   * @return {@code true} if
   *         {@code Equals.of(a, b) && Equals.of(c, d) && Equals.of(e, f)}
   */
  public static boolean of(
      Object a, Object b,
      Object c, Object d,
      Object e, Object f) {
    return of(a, b)
        && of(c, d)
        && of(e, f);
  }

}