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src/java.base/share/classes/java/util/Objects.java

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  1 /*
  2  * Copyright (c) 2009, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 
 26 package java.util;
 27 


 28 import jdk.internal.util.Preconditions;
 29 import jdk.internal.vm.annotation.ForceInline;
 30 
 31 import java.util.function.Supplier;
 32 
 33 /**
 34  * This class consists of {@code static} utility methods for operating
 35  * on objects, or checking certain conditions before operation.  These utilities
 36  * include {@code null}-safe or {@code null}-tolerant methods for computing the
 37  * hash code of an object, returning a string for an object, comparing two
 38  * objects, and checking if indexes or sub-range values are out of bounds.
 39  *
 40  * @since 1.7
 41  */
 42 public final class Objects {
 43     private Objects() {
 44         throw new AssertionError("No java.util.Objects instances for you!");
 45     }
 46 
 47     /**
 48      * {@return {@code true} if the arguments are equal to each other
 49      * and {@code false} otherwise}
 50      * Consequently, if both arguments are {@code null}, {@code true}
 51      * is returned.  Otherwise, if the first argument is not {@code
 52      * null}, equality is determined by calling the {@link
 53      * Object#equals equals} method of the first argument with the
 54      * second argument of this method. Otherwise, {@code false} is
 55      * returned.
 56      *
 57      * @param a an object
 58      * @param b an object to be compared with {@code a} for equality
 59      * @see Object#equals(Object)
 60      */
 61     public static boolean equals(Object a, Object b) {
 62         return (a == b) || (a != null && a.equals(b));





 63     }
 64 
 65    /**
 66     * {@return {@code true} if the arguments are deeply equal to each other
 67     * and {@code false} otherwise}
 68     *
 69     * Two {@code null} values are deeply equal.  If both arguments are
 70     * arrays, the algorithm in {@link Arrays#deepEquals(Object[],
 71     * Object[]) Arrays.deepEquals} is used to determine equality.
 72     * Otherwise, equality is determined by using the {@link
 73     * Object#equals equals} method of the first argument.
 74     *
 75     * @param a an object
 76     * @param b an object to be compared with {@code a} for deep equality
 77     * @see Arrays#deepEquals(Object[], Object[])
 78     * @see Objects#equals(Object, Object)
 79     */
 80     public static boolean deepEquals(Object a, Object b) {
 81         if (a == b)
 82             return true;

160      *
161      * @implNote
162      * This method constructs a string for an object without calling
163      * any overridable methods of the object.
164      *
165      * @implSpec
166      * The method returns a string equivalent to:<br>
167      * {@code o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o))}
168      *
169      * @param o an object
170      * @throws NullPointerException if the argument is null
171      * @see Object#toString
172      * @see System#identityHashCode(Object)
173      * @since 19
174      */
175     public static String toIdentityString(Object o) {
176         requireNonNull(o);
177         return o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o));
178     }
179 

































































































180     /**
181      * {@return 0 if the arguments are identical and {@code
182      * c.compare(a, b)} otherwise}
183      * Consequently, if both arguments are {@code null} 0
184      * is returned.
185      *
186      * <p>Note that if one of the arguments is {@code null}, a {@code
187      * NullPointerException} may or may not be thrown depending on
188      * what ordering policy, if any, the {@link Comparator Comparator}
189      * chooses to have for {@code null} values.
190      *
191      * @param <T> the type of the objects being compared
192      * @param a an object
193      * @param b an object to be compared with {@code a}
194      * @param c the {@code Comparator} to compare the first two arguments
195      * @see Comparable
196      * @see Comparator
197      */
198     public static <T> int compare(T a, T b, Comparator<? super T> c) {
199         return (a == b) ? 0 :  c.compare(a, b);

  1 /*
  2  * Copyright (c) 2009, 2025, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 
 26 package java.util;
 27 
 28 import jdk.internal.javac.PreviewFeature;
 29 import jdk.internal.misc.PreviewFeatures;
 30 import jdk.internal.util.Preconditions;
 31 import jdk.internal.vm.annotation.ForceInline;
 32 
 33 import java.util.function.Supplier;
 34 
 35 /**
 36  * This class consists of {@code static} utility methods for operating
 37  * on objects, or checking certain conditions before operation.  These utilities
 38  * include {@code null}-safe or {@code null}-tolerant methods for computing the
 39  * hash code of an object, returning a string for an object, comparing two
 40  * objects, and checking if indexes or sub-range values are out of bounds.
 41  *
 42  * @since 1.7
 43  */
 44 public final class Objects {
 45     private Objects() {
 46         throw new AssertionError("No java.util.Objects instances for you!");
 47     }
 48 
 49     /**
 50      * {@return {@code true} if the arguments are equal to each other
 51      * and {@code false} otherwise}
 52      * Consequently, if both arguments are {@code null}, {@code true}
 53      * is returned.  Otherwise, if the first argument is not {@code
 54      * null}, equality is determined by calling the {@link
 55      * Object#equals equals} method of the first argument with the
 56      * second argument of this method. Otherwise, {@code false} is
 57      * returned.
 58      *
 59      * @param a an object
 60      * @param b an object to be compared with {@code a} for equality
 61      * @see Object#equals(Object)
 62      */
 63     public static boolean equals(Object a, Object b) {
 64         if (PreviewFeatures.isEnabled()) {
 65             // With --enable-preview avoid acmp
 66             return (a == null) ? b == null : a.equals(b);
 67         } else {
 68             return (a == b) || (a != null && a.equals(b));
 69         }
 70     }
 71 
 72    /**
 73     * {@return {@code true} if the arguments are deeply equal to each other
 74     * and {@code false} otherwise}
 75     *
 76     * Two {@code null} values are deeply equal.  If both arguments are
 77     * arrays, the algorithm in {@link Arrays#deepEquals(Object[],
 78     * Object[]) Arrays.deepEquals} is used to determine equality.
 79     * Otherwise, equality is determined by using the {@link
 80     * Object#equals equals} method of the first argument.
 81     *
 82     * @param a an object
 83     * @param b an object to be compared with {@code a} for deep equality
 84     * @see Arrays#deepEquals(Object[], Object[])
 85     * @see Objects#equals(Object, Object)
 86     */
 87     public static boolean deepEquals(Object a, Object b) {
 88         if (a == b)
 89             return true;

167      *
168      * @implNote
169      * This method constructs a string for an object without calling
170      * any overridable methods of the object.
171      *
172      * @implSpec
173      * The method returns a string equivalent to:<br>
174      * {@code o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o))}
175      *
176      * @param o an object
177      * @throws NullPointerException if the argument is null
178      * @see Object#toString
179      * @see System#identityHashCode(Object)
180      * @since 19
181      */
182     public static String toIdentityString(Object o) {
183         requireNonNull(o);
184         return o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o));
185     }
186 
187    /**
188     * {@return {@code true} if the object is a non-null reference
189     * to an {@linkplain Class#isIdentity() identity object}, otherwise {@code false}}
190     *
191     * @apiNote
192     * If the parameter is {@code null}, there is no object
193     * and hence no class to check for identity; the return is {@code false}.
194     * To test for a {@linkplain Class#isValue() value object} use:
195     * {@snippet type="java" :
196     *     if (obj != null && !Objects.hasIdentity(obj)) {
197     *         // obj is a non-null value object
198     *     }
199     * }
200     * @param obj an object or {@code null}
201     * @since Valhalla
202     */
203    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
204 //    @IntrinsicCandidate
205     public static boolean hasIdentity(Object obj) {
206         return (obj == null) ? false : obj.getClass().isIdentity();
207     }
208 
209    /**
210     * {@return {@code true} if the object is a non-null reference
211     * to a {@linkplain Class#isValue() value object}, otherwise {@code false}}
212     *
213     * @param obj an object or {@code null}
214     * @since Valhalla
215     */
216    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
217 //    @IntrinsicCandidate
218     public static boolean isValueObject(Object obj) {
219         return (obj == null) ? false : obj.getClass().isValue();
220     }
221 
222     /**
223      * Checks that the specified object reference is an identity object.
224      *
225      * @param obj the object reference to check for identity
226      * @param <T> the type of the reference
227      * @return {@code obj} if {@code obj} is an identity object
228      * @throws NullPointerException if {@code obj} is {@code null}
229      * @throws IdentityException if {@code obj} is not an identity object
230      * @since Valhalla
231      */
232     @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
233     @ForceInline
234     public static <T> T requireIdentity(T obj) {
235         Objects.requireNonNull(obj);
236         if (!hasIdentity(obj))
237             throw new IdentityException(obj.getClass());
238         return obj;
239     }
240 
241     /**
242      * Checks that the specified object reference is an identity object.
243      *
244      * @param obj the object reference to check for identity
245      * @param message detail message to be used in the event that an
246      *        {@code IdentityException} is thrown; may be null
247      * @param <T> the type of the reference
248      * @return {@code obj} if {@code obj} is an identity object
249      * @throws NullPointerException if {@code obj} is {@code null}
250      * @throws IdentityException if {@code obj} is not an identity object
251      * @since Valhalla
252      */
253     @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
254     @ForceInline
255     public static <T> T requireIdentity(T obj, String message) {
256         Objects.requireNonNull(obj);
257         if (!hasIdentity(obj))
258             throw new IdentityException(message);
259         return obj;
260     }
261 
262     /**
263      * Checks that the specified object reference is an identity object.
264      *
265      * @param obj the object reference to check for identity
266      * @param messageSupplier supplier of the detail message to be
267      *        used in the event that an {@code IdentityException} is thrown; may be null
268      * @param <T> the type of the reference
269      * @return {@code obj} if {@code obj} is an identity object
270      * @throws NullPointerException if {@code obj} is {@code null}
271      * @throws IdentityException if {@code obj} is not an identity object
272      * @since Valhalla
273      */
274     @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
275     @ForceInline
276     public static <T> T requireIdentity(T obj, Supplier<String> messageSupplier) {
277         Objects.requireNonNull(obj);
278         if (!hasIdentity(obj))
279             throw new IdentityException(messageSupplier == null ?
280                     null : messageSupplier.get());
281         return obj;
282     }
283 
284     /**
285      * {@return 0 if the arguments are identical and {@code
286      * c.compare(a, b)} otherwise}
287      * Consequently, if both arguments are {@code null} 0
288      * is returned.
289      *
290      * <p>Note that if one of the arguments is {@code null}, a {@code
291      * NullPointerException} may or may not be thrown depending on
292      * what ordering policy, if any, the {@link Comparator Comparator}
293      * chooses to have for {@code null} values.
294      *
295      * @param <T> the type of the objects being compared
296      * @param a an object
297      * @param b an object to be compared with {@code a}
298      * @param c the {@code Comparator} to compare the first two arguments
299      * @see Comparable
300      * @see Comparator
301      */
302     public static <T> int compare(T a, T b, Comparator<? super T> c) {
303         return (a == b) ? 0 :  c.compare(a, b);
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