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, 2026, 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 input is a non-null reference
183 * to an object with identity, and {@code false} otherwise}
184 *
185 * <p>If the object is an instance of a concrete {@linkplain Class#isValue()
186 * value class}, it does not have identity and the result will be
187 * {@code false}. All other objects, including arrays, are identity objects
188 * and the result will be {@code true}.
189 *
190 * @apiNote
191 * If the parameter is {@code null}, there is no object
192 * and hence no identity; the result is {@code false}.
193 * To test for a value object use:
194 * {@snippet type="java" :
195 * if (obj != null && !Objects.hasIdentity(obj)) {
196 * // obj is a non-null value object
197 * }
198 * }
199 * @param obj an object or {@code null}
200 * @since Valhalla
201 */
202 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective=true)
203 // @IntrinsicCandidate
204 public static boolean hasIdentity(Object obj) {
205 return (obj == null) ? false : !obj.getClass().isValue();
206 }
207
208 /**
209 * Checks that the specified object reference is an identity object.
210 *
211 * @param obj the object reference to check for identity
212 * @param <T> the type of the reference
213 * @return {@code obj} if {@code obj} is an identity object
214 * @throws NullPointerException if {@code obj} is {@code null}
215 * @throws IdentityException if {@code obj} is not an identity object
216 * @since Valhalla
217 */
218 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
219 @ForceInline
220 public static <T> T requireIdentity(T obj) {
221 Objects.requireNonNull(obj);
222 if (!hasIdentity(obj))
223 throw new IdentityException(obj.getClass());
224 return obj;
225 }
226
227 /**
228 * Checks that the specified object reference is an identity object.
229 *
230 * @param obj the object reference to check for identity
231 * @param message detail message to be used in the event that an
232 * {@code IdentityException} is thrown; may be null
233 * @param <T> the type of the reference
234 * @return {@code obj} if {@code obj} is an identity object
235 * @throws NullPointerException if {@code obj} is {@code null}
236 * @throws IdentityException if {@code obj} is not an identity object
237 * @since Valhalla
238 */
239 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
240 @ForceInline
241 public static <T> T requireIdentity(T obj, String message) {
242 Objects.requireNonNull(obj);
243 if (!hasIdentity(obj))
244 throw new IdentityException(message);
245 return obj;
246 }
247
248 /**
249 * Checks that the specified object reference is an identity object.
250 *
251 * @param obj the object reference to check for identity
252 * @param messageSupplier supplier of the detail message to be
253 * used in the event that an {@code IdentityException} is thrown; may be null
254 * @param <T> the type of the reference
255 * @return {@code obj} if {@code obj} is an identity object
256 * @throws NullPointerException if {@code obj} is {@code null}
257 * @throws IdentityException if {@code obj} is not an identity object
258 * @since Valhalla
259 */
260 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
261 @ForceInline
262 public static <T> T requireIdentity(T obj, Supplier<String> messageSupplier) {
263 Objects.requireNonNull(obj);
264 if (!hasIdentity(obj))
265 throw new IdentityException(messageSupplier == null ?
266 null : messageSupplier.get());
267 return obj;
268 }
269
270 /**
271 * {@return 0 if the arguments are identical and {@code
272 * c.compare(a, b)} otherwise}
273 * Consequently, if both arguments are {@code null} 0
274 * is returned.
275 *
276 * <p>Note that if one of the arguments is {@code null}, a {@code
277 * NullPointerException} may or may not be thrown depending on
278 * what ordering policy, if any, the {@link Comparator Comparator}
279 * chooses to have for {@code null} values.
280 *
281 * @param <T> the type of the objects being compared
282 * @param a an object
283 * @param b an object to be compared with {@code a}
284 * @param c the {@code Comparator} to compare the first two arguments
285 * @see Comparable
286 * @see Comparator
287 */
288 public static <T> int compare(T a, T b, Comparator<? super T> c) {
289 return (a == b) ? 0 : c.compare(a, b);
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