1 /*
2 * Copyright (c) 2009, 2011, 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 /**
29 * This class consists of {@code static} utility methods for operating
30 * on objects. These utilities include {@code null}-safe or {@code
31 * null}-tolerant methods for computing the hash code of an object,
32 * returning a string for an object, and comparing two objects.
33 *
34 * @since 1.7
35 */
36 public final class Objects {
37 private Objects() {
38 throw new AssertionError("No java.util.Objects instances for you!");
39 }
40
41 /**
42 * Returns {@code true} if the arguments are equal to each other
43 * and {@code false} otherwise.
44 * Consequently, if both arguments are {@code null}, {@code true}
45 * is returned and if exactly one argument is {@code null}, {@code
46 * false} is returned. Otherwise, equality is determined by using
47 * the {@link Object#equals equals} method of the first
209 * constructors with multiple parameters, as demonstrated below:
210 * <blockquote><pre>
211 * public Foo(Bar bar, Baz baz) {
212 * this.bar = Objects.requireNonNull(bar, "bar must not be null");
213 * this.baz = Objects.requireNonNull(baz, "baz must not be null");
214 * }
215 * </pre></blockquote>
216 *
217 * @param obj the object reference to check for nullity
218 * @param message detail message to be used in the event that a {@code
219 * NullPointerException} is thrown
220 * @param <T> the type of the reference
221 * @return {@code obj} if not {@code null}
222 * @throws NullPointerException if {@code obj} is {@code null}
223 */
224 public static <T> T requireNonNull(T obj, String message) {
225 if (obj == null)
226 throw new NullPointerException(message);
227 return obj;
228 }
229 }
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1 /*
2 * Copyright (c) 2009, 2013, 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 java.util.function.Supplier;
29
30 /**
31 * This class consists of {@code static} utility methods for operating
32 * on objects. These utilities include {@code null}-safe or {@code
33 * null}-tolerant methods for computing the hash code of an object,
34 * returning a string for an object, and comparing two objects.
35 *
36 * @since 1.7
37 */
38 public final class Objects {
39 private Objects() {
40 throw new AssertionError("No java.util.Objects instances for you!");
41 }
42
43 /**
44 * Returns {@code true} if the arguments are equal to each other
45 * and {@code false} otherwise.
46 * Consequently, if both arguments are {@code null}, {@code true}
47 * is returned and if exactly one argument is {@code null}, {@code
48 * false} is returned. Otherwise, equality is determined by using
49 * the {@link Object#equals equals} method of the first
211 * constructors with multiple parameters, as demonstrated below:
212 * <blockquote><pre>
213 * public Foo(Bar bar, Baz baz) {
214 * this.bar = Objects.requireNonNull(bar, "bar must not be null");
215 * this.baz = Objects.requireNonNull(baz, "baz must not be null");
216 * }
217 * </pre></blockquote>
218 *
219 * @param obj the object reference to check for nullity
220 * @param message detail message to be used in the event that a {@code
221 * NullPointerException} is thrown
222 * @param <T> the type of the reference
223 * @return {@code obj} if not {@code null}
224 * @throws NullPointerException if {@code obj} is {@code null}
225 */
226 public static <T> T requireNonNull(T obj, String message) {
227 if (obj == null)
228 throw new NullPointerException(message);
229 return obj;
230 }
231
232 /**
233 * Checks that the specified object reference is not {@code null} and
234 * throws a customized {@link NullPointerException} if it is.
235 *
236 * <p>Compared to the sibling method {@link requireNonNull(Object,
237 * String}, this methods allows creation of the message to be
238 * deferred until after the null check is made. Note that if the
239 * supplier is provided via a lambda expression, there can be an
240 * overhead involved in creating the supplier. Therefore, while
241 * this method may confer a net performance advantage in the
242 * non-null case, it is most likely to do so if creating the
243 * message string is expensive.
244 *
245 * @param obj the object reference to check for nullity
246 * @param messageSupplier supplier of the detail message to be
247 * used in the event that a {@code NullPointerException} is thrown
248 * @param <T> the type of the reference
249 * @return {@code obj} if not {@code null}
250 * @throws NullPointerException if {@code obj} is {@code null}
251 * @since 1.8
252 */
253 public static <T> T requireNonNull(T obj, Supplier<String> messageSupplier) {
254 if (obj == null)
255 throw new NullPointerException(messageSupplier.get());
256 return obj;
257 }
258 }
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