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 17 package com.android.internal.util; 18 19 import java.util.Arrays; 20 21 /** 22 * Object utility methods. 23 */ 24 public 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
