Hello!
>a private static field corresponding to each component
Final instead of static?
With best regards,
Tagir Valeev
пт, 16 авг. 2019 г., 0:06 Brian Goetz <brian.go...@oracle.com>:
> Draft spec, please comment.
>
>
> /* * Copyright (c) 2019, 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. */package java.lang;
> /** * This is the common base class of all Java language record classes. * *
> <p>More information about records, including descriptions of the * implicitly
> declared methods synthesized by the compiler, can be * found in section 8.10
> of * <cite>The Java™ Language Specification</cite>. * * <p>A <em>record
> class</em> is a shallowly immutable, transparent carrier for * a fixed set of
> values, called the <em>record components</em>. The Java™ * language
> provides concise syntax for declaring record classes, whereby the * record
> components are declared in the record header. The list of record *
> components declared in the record header form the <em>record descriptor</em>.
> * * <p>A record class has the following mandated members: a public
> <em>canonical * constructor</em>, whose descriptor is the same as the record
> descriptor; * a private static field corresponding to each component, whose
> name and * type are the same as that of the component; a public accessor
> method * corresponding to each component, whose name and return type are the
> same as * that of the component. If not explicitly declared in the body of
> the record, * implicit implementations for these members are provided. * *
> <p>The implicit declaration of the canonical constructor initializes the *
> component fields from the corresponding constructor arguments. The implicit
> * declaration of the accessor methods returns the value of the corresponding
> * component field. The implicit declaration of the {@link
> Object#equals(Object)}, * {@link Object#hashCode()}, and {@link
> Object#toString()} methods are derived * from all of the component fields. *
> * <p>The primary reasons to provide an explicit declaration for the *
> canonical constructor or accessor methods are to validate constructor *
> arguments, perform defensive copies on mutable components, or normalize
> groups * of components (such as reducing a rational number to lowest terms.)
> If any * of these are provided explicitly. * * <p>For all record classes, the
> following invariant must hold: if a record R's * components are {@code c1,
> c2, ... cn}, then if a record instance is copied * as follows: * <pre> *
> R copy = new R(r.c1(), r.c2(), ..., r.cn()); * </pre> * then it must be the
> case that {@code r.equals(copy)}. * * @jls 8.10 * @since 14 */public abstract
> class Record {
> /** * Indicates whether some other object is "equal to" this one. In
> addition * to the general contract of {@link Object#equals(Object)},
> * record classes must further participate in the invariant that when * a
> record instance is "copied" by passing the result of the record component
> * accessor methods to the canonical constructor, the resulting copy is *
> equal to the original instance. * * @implNote * The implicitly
> provided implementation returns {@code true} if and * only if the
> argument is an instance of the same record type as this object, * and
> each component of this record is equal to the corresponding component *
> of the argument, according to {@link Object#equals(Object)} for components
> * whose types are reference types, and {@code ==} for components whose *
> types are primitive types. * * @see Object#equals(Object) *
> * @param obj the reference object with which to compare. * @return
> {@code true} if this object is the same as the obj * argument;
> {@code false} otherwise. */ @Override public abstract boolean
> equals(Object obj);
>
> /** * {@inheritDoc} * * @implNote * The implicitly
> provided implementation returns a hash code value derived * by combining
> the hash code value for all the components, according to * {@link
> Object#hashCode()} for components whose types are reference types, * or
> the primitive wrapper hash code for components whose types are primitive
> * types. * * @see Object#hashCode() * * @return a hash
> code value for this object. */ @Override public abstract int
> hashCode();
>
> /** * {@inheritDoc} * * @implNote * The implicitly
> provided implementation returns a string that is derived * from the name
> of the record class and the names and string representations * of all the
> components, according to {@link Object#toString()} for components * whose
> types are reference types, and the primitive wrapper {@code toString} *
> method for components whose types are primitive types. * * @see
> Object#toString() () * * @return a string representation of the
> object. */ @Override public abstract String toString();
> }
>
>
