1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.internal.util;
18
19import java.util.Arrays;
20
21/**
22 * Object utility methods.
23 */
24public class Objects {
25
26    /**
27     * Determines whether two possibly-null objects are equal. Returns:
28     *
29     * <ul>
30     * <li>{@code true} if {@code a} and {@code b} are both null.
31     * <li>{@code true} if {@code a} and {@code b} are both non-null and they are
32     *     equal according to {@link Object#equals(Object)}.
33     * <li>{@code false} in all other situations.
34     * </ul>
35     *
36     * <p>This assumes that any non-null objects passed to this function conform
37     * to the {@code equals()} contract.
38     */
39    public static boolean equal(Object a, Object b) {
40        return a == b || (a != null && a.equals(b));
41    }
42
43    /**
44     * Generates a hash code for multiple values. The hash code is generated by
45     * calling {@link Arrays#hashCode(Object[])}.
46     *
47     * <p>This is useful for implementing {@link Object#hashCode()}. For example,
48     * in an object that has three properties, {@code x}, {@code y}, and
49     * {@code z}, one could write:
50     * <pre>
51     * public int hashCode() {
52     *   return Objects.hashCode(getX(), getY(), getZ());
53     * }</pre>
54     *
55     * <b>Warning</b>: When a single object is supplied, the returned hash code
56     * does not equal the hash code of that object.
57     */
58    public static int hashCode(Object... objects) {
59        return Arrays.hashCode(objects);
60    }
61
62}
63