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Alan Bateman 2009-10-10 10:14:51 +01:00
commit fb306e5742
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1
jdk/make/java/java/FILES_java.gmk
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@ -258,6 +258,7 @@ JAVA_JAVA_java = \
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 \

110
jdk/src/share/classes/java/util/Objects.java Normal file
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@ -0,0 +1,110 @@
/*
* 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.
*
* @param a an object
* @param b an object to be compared with {@code a} for equality
* @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.
*
* @param o an object
* @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.
*
* @param o an object
* @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.
*
* <p>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.
*
* @param <T> the type of the objects being compared
* @param a an object
* @param b an object to be compared with {@code a}
* @param c the {@code Comparator} to compare the first two arguments
* @return 0 if the arguments are identical and {@code
* c.compare(a, b)} otherwise.
* @see Comparable
* @see Comparator
*/
public static <T> int compare(T a, T b, Comparator<? super T> c) {
return (a == b) ? 0 : c.compare(a, b);
}
}

105
jdk/test/java/util/Objects/BasicObjectsTest.java Normal file
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@ -0,0 +1,105 @@
/*
* 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.
*
* 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.
*/
/*
* @test
* @bug 6797535
* @summary Basic tests for methods in java.util.Objects
* @author Joseph D. Darcy
*/
import java.util.*;
public class BasicObjectsTest {
public static void main(String... args) {
int errors = 0;
errors += testEquals();
errors += testHashCode();
errors += testToString();
errors += testCompare();
if (errors > 0 )
throw new RuntimeException();
}
private static int testEquals() {
int errors = 0;
Object[] values = {null, "42", 42};
for(int i = 0; i < values.length; i++)
for(int j = 0; j < values.length; j++) {
boolean expected = (i == j);
Object a = values[i];
Object b = values[j];
boolean result = Objects.equals(a, b);
if (result != expected) {
errors++;
System.err.printf("When equating %s to %s, got %b instead of %b%n.",
a, b, result, expected);
}
}
return errors;
}
private static int testHashCode() {
int errors = 0;
errors += (Objects.hashCode(null) == 0 ) ? 0 : 1;
String s = "42";
errors += (Objects.hashCode(s) == s.hashCode() ) ? 0 : 1;
return errors;
}
private static int testToString() {
int errors = 0;
errors += ("null".equals(Objects.toString(null)) ) ? 0 : 1;
String s = "Some string";
errors += (s.equals(Objects.toString(s)) ) ? 0 : 1;
return errors;
}
private static int testCompare() {
int errors = 0;
String[] values = {"e. e. cummings", "zzz"};
String[] VALUES = {"E. E. Cummings", "ZZZ"};
errors += compareTest(null, null, 0);
for(int i = 0; i < values.length; i++) {
String a = values[i];
errors += compareTest(a, a, 0);
for(int j = 0; j < VALUES.length; j++) {
int expected = Integer.compare(i, j);
String b = VALUES[j];
errors += compareTest(a, b, expected);
}
}
return errors;
}
private static int compareTest(String a, String b, int expected) {
int errors = 0;
int result = Objects.compare(a, b, String.CASE_INSENSITIVE_ORDER);
if (Integer.signum(result) != Integer.signum(expected)) {
errors++;
System.err.printf("When comparing %s to %s, got %d instead of %d%n.",
a, b, result, expected);
}
return errors;
}
}