| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * 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 androidx.core.util; |
| |
| import android.os.Build; |
| |
| import androidx.annotation.Nullable; |
| |
| import java.util.Arrays; |
| import java.util.Objects; |
| |
| /** |
| * This class consists of static utility methods for operating on objects. |
| */ |
| public class ObjectsCompat { |
| private ObjectsCompat() { |
| // Non-instantiable. |
| } |
| |
| /** |
| * Returns {@code true} if the arguments are equal to each other |
| * and {@code false} otherwise. |
| * <p> |
| * Consequently, if both arguments are {@code null}, {@code true} |
| * is returned and if exactly one argument is {@code null}, {@code |
| * false} is returned. Otherwise, equality is determined by using |
| * the {@link Object#equals equals} method of the first |
| * argument. |
| * |
| * @param a an object |
| * @param b an object to be compared with {@code a} for equality |
| * @return {@code true} if the arguments are equal to each other |
| * and {@code false} otherwise |
| * @see Object#equals(Object) |
| */ |
| public static boolean equals(@Nullable Object a, @Nullable Object b) { |
| if (Build.VERSION.SDK_INT >= 19) { |
| return Objects.equals(a, b); |
| } else { |
| return (a == b) || (a != null && a.equals(b)); |
| } |
| } |
| |
| /** |
| * Returns the hash code of a non-{@code null} argument and 0 for a {@code null} argument. |
| * |
| * @param o an object |
| * @return the hash code of a non-{@code null} argument and 0 for a {@code null} argument |
| * @see Object#hashCode |
| */ |
| public static int hashCode(@Nullable Object o) { |
| return o != null ? o.hashCode() : 0; |
| } |
| |
| /** |
| * Generates a hash code for a sequence of input values. The hash code is generated as if all |
| * the input values were placed into an array, and that array were hashed by calling |
| * {@link Arrays#hashCode(Object[])}. |
| * |
| * <p>This method is useful for implementing {@link Object#hashCode()} on objects containing |
| * multiple fields. For example, if an object that has three fields, {@code x}, {@code y}, and |
| * {@code z}, one could write: |
| * |
| * <blockquote><pre> |
| * @Override public int hashCode() { |
| * return ObjectsCompat.hash(x, y, z); |
| * } |
| * </pre></blockquote> |
| * |
| * <b>Warning: When a single object reference is supplied, the returned value does not equal the |
| * hash code of that object reference.</b> This value can be computed by calling |
| * {@link #hashCode(Object)}. |
| * |
| * @param values the values to be hashed |
| * @return a hash value of the sequence of input values |
| * @see Arrays#hashCode(Object[]) |
| */ |
| public static int hash(@Nullable Object... values) { |
| if (Build.VERSION.SDK_INT >= 19) { |
| return Objects.hash(values); |
| } else { |
| return Arrays.hashCode(values); |
| } |
| } |
| } |