/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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 com.google.common.base;

import com.google.common.annotations.GwtCompatible;
import java.util.Arrays;
import org.checkerframework.checker.nullness.qual.Nullable;

Helper functions that can operate on any Object. 
See the Guava User Guide on writing Object methods with Objects.
Author:
Laurence Gonsalves
Since:
2.0/**
 * Helper functions that can operate on any {@code Object}.
 *
 * <p>See the Guava User Guide on <a
 * href="https://github.com/google/guava/wiki/CommonObjectUtilitiesExplained">writing {@code Object}
 * methods with {@code Objects}</a>.
 *
 * @author Laurence Gonsalves
 * @since 2.0
 */
@GwtCompatible
public final class Objects extends ExtraObjectsMethodsForWeb {
  private Objects() {}

  
Determines whether two possibly-null objects are equal. Returns:

  
true if a and b are both null. 
true if a and b are both non-null and they are equal according to Object.equals(Object). 
false in all other situations. 
This assumes that any non-null objects passed to this function conform to the 
equals() contract. 
Note for Java 7 and later: This method should be treated as deprecated; use Object.equals instead. /**
   * Determines whether two possibly-null objects are equal. Returns:
   *
   * <ul>
   *   <li>{@code true} if {@code a} and {@code b} are both null.
   *   <li>{@code true} if {@code a} and {@code b} are both non-null and they are equal according to
   *       {@link Object#equals(Object)}.
   *   <li>{@code false} in all other situations.
   * </ul>
   *
   * <p>This assumes that any non-null objects passed to this function conform to the {@code
   * equals()} contract.
   *
   * <p><b>Note for Java 7 and later:</b> This method should be treated as deprecated; use {@link
   * java.util.Objects#equals} instead.
   */
  public static boolean equal(@Nullable Object a, @Nullable Object b) {
    return a == b || (a != null && a.equals(b));
  }

  
Generates a hash code for multiple values. The hash code is generated by calling Arrays.hashCode(Object[]). Note that array arguments to this method, with the exception of a single Object array, do not get any special handling; their hash codes are based on identity and not contents. 
This is useful for implementing Object.hashCode(). For example, in an object that has three properties, x, y, and z, one could write: 

public int hashCode() {
  return Objects.hashCode(getX(), getY(), getZ());
 }

Warning: When a single object is supplied, the returned hash code does not equal the
hash code of that object.
Note for Java 7 and later: This method should be treated as deprecated; use Objects.hash instead. /**
   * Generates a hash code for multiple values. The hash code is generated by calling {@link
   * Arrays#hashCode(Object[])}. Note that array arguments to this method, with the exception of a
   * single Object array, do not get any special handling; their hash codes are based on identity
   * and not contents.
   *
   * <p>This is useful for implementing {@link Object#hashCode()}. For example, in an object that
   * has three properties, {@code x}, {@code y}, and {@code z}, one could write:
   *
   * <pre>{@code
   * public int hashCode() {
   *   return Objects.hashCode(getX(), getY(), getZ());
   * }
   * }</pre>
   *
   * <p><b>Warning:</b> When a single object is supplied, the returned hash code does not equal the
   * hash code of that object.
   *
   * <p><b>Note for Java 7 and later:</b> This method should be treated as deprecated; use {@link
   * java.util.Objects#hash} instead.
   */
  public static int hashCode(Object @Nullable... objects) {
    return Arrays.hashCode(objects);
  }
}