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 /**
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);
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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.util.Preconditions;
30 import jdk.internal.vm.annotation.ForceInline;
31
32 import java.util.function.Supplier;
33
34 /**
35 * This class consists of {@code static} utility methods for operating
36 * on objects, or checking certain conditions before operation. These utilities
37 * include {@code null}-safe or {@code null}-tolerant methods for computing the
38 * hash code of an object, returning a string for an object, comparing two
39 * objects, and checking if indexes or sub-range values are out of bounds.
40 *
41 * @since 1.7
42 */
43 public final class Objects {
44 private Objects() {
45 throw new AssertionError("No java.util.Objects instances for you!");
46 }
47
48 /**
161 *
162 * @implNote
163 * This method constructs a string for an object without calling
164 * any overridable methods of the object.
165 *
166 * @implSpec
167 * The method returns a string equivalent to:<br>
168 * {@code o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o))}
169 *
170 * @param o an object
171 * @throws NullPointerException if the argument is null
172 * @see Object#toString
173 * @see System#identityHashCode(Object)
174 * @since 19
175 */
176 public static String toIdentityString(Object o) {
177 requireNonNull(o);
178 return o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o));
179 }
180
181 /**
182 * {@return {@code true} if the object is a non-null reference
183 * to an {@linkplain Class#isIdentity() identity object}, otherwise {@code false}}
184 *
185 * @apiNote
186 * If the parameter is {@code null}, there is no object
187 * and hence no class to check for identity; the return is {@code false}.
188 * To test for a {@linkplain Class#isValue() value object} use:
189 * {@snippet type="java" :
190 * if (obj != null && !Objects.hasIdentity(obj)) {
191 * // obj is a non-null value object
192 * }
193 * }
194 * @param obj an object or {@code null}
195 * @since Valhalla
196 */
197 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
198 // @IntrinsicCandidate
199 public static boolean hasIdentity(Object obj) {
200 return (obj == null) ? false : obj.getClass().isIdentity();
201 }
202
203 /**
204 * {@return {@code true} if the object is a non-null reference
205 * to a {@linkplain Class#isValue() value object}, otherwise {@code false}}
206 *
207 * @param obj an object or {@code null}
208 * @since Valhalla
209 */
210 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
211 // @IntrinsicCandidate
212 public static boolean isValueObject(Object obj) {
213 return (obj == null) ? false : obj.getClass().isValue();
214 }
215
216 /**
217 * Checks that the specified object reference is an identity object.
218 *
219 * @param obj the object reference to check for identity
220 * @param <T> the type of the reference
221 * @return {@code obj} if {@code obj} is an identity object
222 * @throws NullPointerException if {@code obj} is {@code null}
223 * @throws IdentityException if {@code obj} is not an identity object
224 * @since Valhalla
225 */
226 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
227 @ForceInline
228 public static <T> T requireIdentity(T obj) {
229 Objects.requireNonNull(obj);
230 if (!hasIdentity(obj))
231 throw new IdentityException(obj.getClass());
232 return obj;
233 }
234
235 /**
236 * Checks that the specified object reference is an identity object.
237 *
238 * @param obj the object reference to check for identity
239 * @param message detail message to be used in the event that an
240 * {@code IdentityException} is thrown; may be null
241 * @param <T> the type of the reference
242 * @return {@code obj} if {@code obj} is an identity object
243 * @throws NullPointerException if {@code obj} is {@code null}
244 * @throws IdentityException if {@code obj} is not an identity object
245 * @since Valhalla
246 */
247 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
248 @ForceInline
249 public static <T> T requireIdentity(T obj, String message) {
250 Objects.requireNonNull(obj);
251 if (!hasIdentity(obj))
252 throw new IdentityException(message);
253 return obj;
254 }
255
256 /**
257 * Checks that the specified object reference is an identity object.
258 *
259 * @param obj the object reference to check for identity
260 * @param messageSupplier supplier of the detail message to be
261 * used in the event that an {@code IdentityException} is thrown; may be null
262 * @param <T> the type of the reference
263 * @return {@code obj} if {@code obj} is an identity object
264 * @throws NullPointerException if {@code obj} is {@code null}
265 * @throws IdentityException if {@code obj} is not an identity object
266 * @since Valhalla
267 */
268 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
269 @ForceInline
270 public static <T> T requireIdentity(T obj, Supplier<String> messageSupplier) {
271 Objects.requireNonNull(obj);
272 if (!hasIdentity(obj))
273 throw new IdentityException(messageSupplier == null ?
274 null : messageSupplier.get());
275 return obj;
276 }
277
278 /**
279 * {@return 0 if the arguments are identical and {@code
280 * c.compare(a, b)} otherwise}
281 * Consequently, if both arguments are {@code null} 0
282 * is returned.
283 *
284 * <p>Note that if one of the arguments is {@code null}, a {@code
285 * NullPointerException} may or may not be thrown depending on
286 * what ordering policy, if any, the {@link Comparator Comparator}
287 * chooses to have for {@code null} values.
288 *
289 * @param <T> the type of the objects being compared
290 * @param a an object
291 * @param b an object to be compared with {@code a}
292 * @param c the {@code Comparator} to compare the first two arguments
293 * @see Comparable
294 * @see Comparator
295 */
296 public static <T> int compare(T a, T b, Comparator<? super T> c) {
297 return (a == b) ? 0 : c.compare(a, b);
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