1.1 --- a/emul/compact/src/main/java/java/util/Objects.java Fri Mar 22 16:59:47 2013 +0100
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,229 +0,0 @@
1.4 -/*
1.5 - * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.
1.6 - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 - *
1.8 - * This code is free software; you can redistribute it and/or modify it
1.9 - * under the terms of the GNU General Public License version 2 only, as
1.10 - * published by the Free Software Foundation. Oracle designates this
1.11 - * particular file as subject to the "Classpath" exception as provided
1.12 - * by Oracle in the LICENSE file that accompanied this code.
1.13 - *
1.14 - * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 - * version 2 for more details (a copy is included in the LICENSE file that
1.18 - * accompanied this code).
1.19 - *
1.20 - * You should have received a copy of the GNU General Public License version
1.21 - * 2 along with this work; if not, write to the Free Software Foundation,
1.22 - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 - *
1.24 - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 - * or visit www.oracle.com if you need additional information or have any
1.26 - * questions.
1.27 - */
1.28 -
1.29 -package java.util;
1.30 -
1.31 -/**
1.32 - * This class consists of {@code static} utility methods for operating
1.33 - * on objects. These utilities include {@code null}-safe or {@code
1.34 - * null}-tolerant methods for computing the hash code of an object,
1.35 - * returning a string for an object, and comparing two objects.
1.36 - *
1.37 - * @since 1.7
1.38 - */
1.39 -public final class Objects {
1.40 - private Objects() {
1.41 - throw new AssertionError("No java.util.Objects instances for you!");
1.42 - }
1.43 -
1.44 - /**
1.45 - * Returns {@code true} if the arguments are equal to each other
1.46 - * and {@code false} otherwise.
1.47 - * Consequently, if both arguments are {@code null}, {@code true}
1.48 - * is returned and if exactly one argument is {@code null}, {@code
1.49 - * false} is returned. Otherwise, equality is determined by using
1.50 - * the {@link Object#equals equals} method of the first
1.51 - * argument.
1.52 - *
1.53 - * @param a an object
1.54 - * @param b an object to be compared with {@code a} for equality
1.55 - * @return {@code true} if the arguments are equal to each other
1.56 - * and {@code false} otherwise
1.57 - * @see Object#equals(Object)
1.58 - */
1.59 - public static boolean equals(Object a, Object b) {
1.60 - return (a == b) || (a != null && a.equals(b));
1.61 - }
1.62 -
1.63 - /**
1.64 - * Returns {@code true} if the arguments are deeply equal to each other
1.65 - * and {@code false} otherwise.
1.66 - *
1.67 - * Two {@code null} values are deeply equal. If both arguments are
1.68 - * arrays, the algorithm in {@link Arrays#deepEquals(Object[],
1.69 - * Object[]) Arrays.deepEquals} is used to determine equality.
1.70 - * Otherwise, equality is determined by using the {@link
1.71 - * Object#equals equals} method of the first argument.
1.72 - *
1.73 - * @param a an object
1.74 - * @param b an object to be compared with {@code a} for deep equality
1.75 - * @return {@code true} if the arguments are deeply equal to each other
1.76 - * and {@code false} otherwise
1.77 - * @see Arrays#deepEquals(Object[], Object[])
1.78 - * @see Objects#equals(Object, Object)
1.79 - */
1.80 - public static boolean deepEquals(Object a, Object b) {
1.81 - if (a == b)
1.82 - return true;
1.83 - else if (a == null || b == null)
1.84 - return false;
1.85 - else
1.86 - return Arrays.deepEquals0(a, b);
1.87 - }
1.88 -
1.89 - /**
1.90 - * Returns the hash code of a non-{@code null} argument and 0 for
1.91 - * a {@code null} argument.
1.92 - *
1.93 - * @param o an object
1.94 - * @return the hash code of a non-{@code null} argument and 0 for
1.95 - * a {@code null} argument
1.96 - * @see Object#hashCode
1.97 - */
1.98 - public static int hashCode(Object o) {
1.99 - return o != null ? o.hashCode() : 0;
1.100 - }
1.101 -
1.102 - /**
1.103 - * Generates a hash code for a sequence of input values. The hash
1.104 - * code is generated as if all the input values were placed into an
1.105 - * array, and that array were hashed by calling {@link
1.106 - * Arrays#hashCode(Object[])}.
1.107 - *
1.108 - * <p>This method is useful for implementing {@link
1.109 - * Object#hashCode()} on objects containing multiple fields. For
1.110 - * example, if an object that has three fields, {@code x}, {@code
1.111 - * y}, and {@code z}, one could write:
1.112 - *
1.113 - * <blockquote><pre>
1.114 - * @Override public int hashCode() {
1.115 - * return Objects.hash(x, y, z);
1.116 - * }
1.117 - * </pre></blockquote>
1.118 - *
1.119 - * <b>Warning: When a single object reference is supplied, the returned
1.120 - * value does not equal the hash code of that object reference.</b> This
1.121 - * value can be computed by calling {@link #hashCode(Object)}.
1.122 - *
1.123 - * @param values the values to be hashed
1.124 - * @return a hash value of the sequence of input values
1.125 - * @see Arrays#hashCode(Object[])
1.126 - * @see List#hashCode
1.127 - */
1.128 - public static int hash(Object... values) {
1.129 - return Arrays.hashCode(values);
1.130 - }
1.131 -
1.132 - /**
1.133 - * Returns the result of calling {@code toString} for a non-{@code
1.134 - * null} argument and {@code "null"} for a {@code null} argument.
1.135 - *
1.136 - * @param o an object
1.137 - * @return the result of calling {@code toString} for a non-{@code
1.138 - * null} argument and {@code "null"} for a {@code null} argument
1.139 - * @see Object#toString
1.140 - * @see String#valueOf(Object)
1.141 - */
1.142 - public static String toString(Object o) {
1.143 - return String.valueOf(o);
1.144 - }
1.145 -
1.146 - /**
1.147 - * Returns the result of calling {@code toString} on the first
1.148 - * argument if the first argument is not {@code null} and returns
1.149 - * the second argument otherwise.
1.150 - *
1.151 - * @param o an object
1.152 - * @param nullDefault string to return if the first argument is
1.153 - * {@code null}
1.154 - * @return the result of calling {@code toString} on the first
1.155 - * argument if it is not {@code null} and the second argument
1.156 - * otherwise.
1.157 - * @see Objects#toString(Object)
1.158 - */
1.159 - public static String toString(Object o, String nullDefault) {
1.160 - return (o != null) ? o.toString() : nullDefault;
1.161 - }
1.162 -
1.163 - /**
1.164 - * Returns 0 if the arguments are identical and {@code
1.165 - * c.compare(a, b)} otherwise.
1.166 - * Consequently, if both arguments are {@code null} 0
1.167 - * is returned.
1.168 - *
1.169 - * <p>Note that if one of the arguments is {@code null}, a {@code
1.170 - * NullPointerException} may or may not be thrown depending on
1.171 - * what ordering policy, if any, the {@link Comparator Comparator}
1.172 - * chooses to have for {@code null} values.
1.173 - *
1.174 - * @param <T> the type of the objects being compared
1.175 - * @param a an object
1.176 - * @param b an object to be compared with {@code a}
1.177 - * @param c the {@code Comparator} to compare the first two arguments
1.178 - * @return 0 if the arguments are identical and {@code
1.179 - * c.compare(a, b)} otherwise.
1.180 - * @see Comparable
1.181 - * @see Comparator
1.182 - */
1.183 - public static <T> int compare(T a, T b, Comparator<? super T> c) {
1.184 - return (a == b) ? 0 : c.compare(a, b);
1.185 - }
1.186 -
1.187 - /**
1.188 - * Checks that the specified object reference is not {@code null}. This
1.189 - * method is designed primarily for doing parameter validation in methods
1.190 - * and constructors, as demonstrated below:
1.191 - * <blockquote><pre>
1.192 - * public Foo(Bar bar) {
1.193 - * this.bar = Objects.requireNonNull(bar);
1.194 - * }
1.195 - * </pre></blockquote>
1.196 - *
1.197 - * @param obj the object reference to check for nullity
1.198 - * @param <T> the type of the reference
1.199 - * @return {@code obj} if not {@code null}
1.200 - * @throws NullPointerException if {@code obj} is {@code null}
1.201 - */
1.202 - public static <T> T requireNonNull(T obj) {
1.203 - if (obj == null)
1.204 - throw new NullPointerException();
1.205 - return obj;
1.206 - }
1.207 -
1.208 - /**
1.209 - * Checks that the specified object reference is not {@code null} and
1.210 - * throws a customized {@link NullPointerException} if it is. This method
1.211 - * is designed primarily for doing parameter validation in methods and
1.212 - * constructors with multiple parameters, as demonstrated below:
1.213 - * <blockquote><pre>
1.214 - * public Foo(Bar bar, Baz baz) {
1.215 - * this.bar = Objects.requireNonNull(bar, "bar must not be null");
1.216 - * this.baz = Objects.requireNonNull(baz, "baz must not be null");
1.217 - * }
1.218 - * </pre></blockquote>
1.219 - *
1.220 - * @param obj the object reference to check for nullity
1.221 - * @param message detail message to be used in the event that a {@code
1.222 - * NullPointerException} is thrown
1.223 - * @param <T> the type of the reference
1.224 - * @return {@code obj} if not {@code null}
1.225 - * @throws NullPointerException if {@code obj} is {@code null}
1.226 - */
1.227 - public static <T> T requireNonNull(T obj, String message) {
1.228 - if (obj == null)
1.229 - throw new NullPointerException(message);
1.230 - return obj;
1.231 - }
1.232 -}