First round of java.util.Objects for code review (bug 6797535) (original) (raw)

Marek Kozieł develop4lasu at gmail.com
Fri Oct 9 06:58:56 UTC 2009

2009/10/8 Joseph D. Darcy <Joe.Darcy at sun.com>:

Hello.

Please code review the first-round of java.util.Objects; the patch is below: http://cr.openjdk.java.net/~darcy/6797535.0/ -Joe --- old/make/java/java/FILESjava.gmk   2009-10-08 11:04:03.000000000 -0700 +++ new/make/java/java/FILESjava.gmk   2009-10-08 11:04:02.000000000 -0700 @@ -258,6 +258,7 @@  _java/util/ServiceConfigurationError.java _  _java/util/Timer.java _  _java/util/TimerTask.java _ _+    java/util/Objects.java _  _java/util/UUID.java _  _java/util/concurrent/AbstractExecutorService.java _  _java/util/concurrent/ArrayBlockingQueue.java _ --- /dev/null   2009-07-06 20:02:10.000000000 -0700 +++ new/src/share/classes/java/util/Objects.java        2009-10-08 11:04:03.000000000 -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)); +    }

Hello, I would suggest other implementation of equals method:

public static boolean equals(Object a, Object b) {
    if (a == null) return (b == null ? true : b.equals(null));
    if (b == null) return a.equals(null);
    return a.equals(b);
}

This one could cover case when null is considered as object in object equals method, while in not time implementation result might depend from arguments order:

class Boo {
    public String	data;

    @Override
    public boolean equals(Object obj) {
        if (obj == null) return (data == null);//
        ...
    }
}

-- Regards. Lasu aka Marek Kozieł

http://lasu2string.blogspot.com/

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