java8.lang.package-info Maven / Gradle / Ivy

Go to download

/* * Copyright (c) 2012, 2013, Oracle and/or its affiliates. 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. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /** * Provides classes for some of the new static methods that were added in Java 8. * * Value-based Classes * * Some classes, such as {@code java8.util.Optional}, are value-based. Instances * of a value-based class: * * * are final and immutable (though may contain references to mutable objects); * have implementations of equals, hashCode, and toString which are computed * solely from the instance's state and not from its identity or the state of * any other object or variable; * make no use of identity-sensitive operations such as reference equality * (==) between instances, identity hash code of instances, or synchronization * on an instances's intrinsic lock; * are considered equal solely based on equals(), not based on reference * equality (==); * do not have accessible constructors, but are instead instantiated through * factory methods which make no committment as to the identity of returned * instances; * are freely substitutable when equal, meaning that interchanging any two * instances x and y that are equal according to equals() in any computation or * method invocation should produce no visible change in behavior. * * * A program may produce unpredictable results if it attempts to distinguish two * references to equal values of a value-based class, whether directly via * reference equality or indirectly via an appeal to synchronization, identity * hashing, serialization, or any other identity-sensitive mechanism. Use of such * identity-sensitive operations on instances of value-based classes may have * unpredictable effects and should be avoided. *

* * @since 1.8 */ package java8.lang;