--- /dev/null 2009-07-06 20:02:10.000000000 -0700 +++ new/src/share/classes/java/util/Objects.java 2009-10-08 11:09:00.000000000 -0700 @@ -0,0 +1,102 @@ +/* + * Copyright 2009 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Sun designates this + * particular file as subject to the "Classpath" exception as provided + * by Sun in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + */ + +package java.util; + +/** + * This class consists of {@code static} utility methods for operating + * on objects. These utilities include {@code null}-safe or {@code + * null}-tolerant methods for computing the hash code of an object, + * returning a string for an object, and comparing two objects. + * + * @since 1.7 + */ +public class Objects { + private Objects() { + throw new AssertionError("No java.util.Objects instances for you!"); + } + + /** + * Returns {@code true} if the arguments are equal to each other + * and {@code false} otherwise. + * 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. + * + * @return {@code true} if the arguments are equal to each other + * and {@code false} otherwise + * @see Object#equals(Object) + */ + public static boolean equals(Object a, Object b) { + 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. + * + * @return the hash code of a non-{@code null} argument and 0 for + * a {@code null} argument + * @see Object#hashCode + */ + public static int hashCode(Object o) { + return o != null ? o.hashCode() : 0; + } + + /** + * Returns the result of calling {@code toString} for a non-{@code + * null} argument and {@code "null"} for a {@code null} argument. + * + * @return the result of calling {@code toString} for a non-{@code + * null} argument and {@code "null"} for a {@code null} argument + * @see Object#toString + * @see String#valueOf(Object) + */ + public static String toString(Object o) { + return String.valueOf(o); + } + + /** + * Returns 0 if the arguments are identical and {@code + * c.compare(a, b)} otherwise. + * Consequently, if both arguments are {@code null} 0 + * is returned. + * + *

Note that if one of the arguments is {@code null}, a {@code + * NullPointerException} may or may not be thrown depending on + * what ordering policy, if any, the {@link Comparator Comparator} + * chooses to have for {@code null} values. + * + * @return 0 if the arguments are identical and {@code + * c.compare(a, b)} otherwise. + * @see Comparable + * @see Comparator + */ + public static int compare(T a, T b, Comparator c) { + return (a == b) ? 0 : c.compare(a, b); + } +}