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src/java.base/share/classes/java/lang/Short.java

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  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.lang;
 27 
 28 import jdk.internal.misc.CDS;


 29 import jdk.internal.vm.annotation.IntrinsicCandidate;
 30 import jdk.internal.vm.annotation.Stable;
 31 
 32 import java.lang.constant.Constable;
 33 import java.lang.constant.DynamicConstantDesc;
 34 import java.util.Optional;
 35 
 36 import static java.lang.constant.ConstantDescs.BSM_EXPLICIT_CAST;
 37 import static java.lang.constant.ConstantDescs.CD_int;
 38 import static java.lang.constant.ConstantDescs.CD_short;
 39 import static java.lang.constant.ConstantDescs.DEFAULT_NAME;
 40 
 41 /**
 42  * The {@code Short} class is the {@linkplain
 43  * java.lang##wrapperClass wrapper class} for values of the primitive
 44  * type {@code short}. An object of type {@code Short} contains a
 45  * single field whose type is {@code short}.
 46  *
 47  * <p>In addition, this class provides several methods for converting
 48  * a {@code short} to a {@code String} and a {@code String} to a
 49  * {@code short}, as well as other constants and methods useful when
 50  * dealing with a {@code short}.
 51  *
 52  * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 53  * class; programmers should treat instances that are
 54  * {@linkplain #equals(Object) equal} as interchangeable and should not
 55  * use instances for synchronization, or unpredictable behavior may
 56  * occur. For example, in a future release, synchronization may fail.








 57  *
 58  * @see     java.lang.Number
 59  * @since   1.1
 60  */

 61 @jdk.internal.ValueBased
 62 public final class Short extends Number implements Comparable<Short>, Constable {
 63 
 64     /**
 65      * A constant holding the minimum value a {@code short} can
 66      * have, -2<sup>15</sup>.
 67      */
 68     public static final short   MIN_VALUE = -32768;
 69 
 70     /**
 71      * A constant holding the maximum value a {@code short} can
 72      * have, 2<sup>15</sup>-1.
 73      */
 74     public static final short   MAX_VALUE = 32767;
 75 
 76     /**
 77      * The {@code Class} instance representing the primitive type
 78      * {@code short}.
 79      */
 80     public static final Class<Short> TYPE = Class.getPrimitiveClass("short");

241             int size = -(-128) + 127 + 1;
242 
243             // Load and use the archived cache if it exists
244             CDS.initializeFromArchive(ShortCache.class);
245             if (archivedCache == null) {
246                 Short[] c = new Short[size];
247                 short value = -128;
248                 for(int i = 0; i < size; i++) {
249                     c[i] = new Short(value++);
250                 }
251                 archivedCache = c;
252             }
253             cache = archivedCache;
254             assert cache.length == size;
255         }
256     }
257 
258     /**
259      * Returns a {@code Short} instance representing the specified
260      * {@code short} value.
261      * If a new {@code Short} instance is not required, this method
262      * should generally be used in preference to the constructor
263      * {@link #Short(short)}, as this method is likely to yield
264      * significantly better space and time performance by caching
265      * frequently requested values.
266      *
267      * This method will always cache values in the range -128 to 127,
268      * inclusive, and may cache other values outside of this range.











269      *
270      * @param  s a short value.
271      * @return a {@code Short} instance representing {@code s}.
272      * @since  1.5
273      */
274     @IntrinsicCandidate

275     public static Short valueOf(short s) {
276         final int offset = 128;
277         int sAsInt = s;
278         if (sAsInt >= -128 && sAsInt <= 127) { // must cache
279             return ShortCache.cache[sAsInt + offset];


280         }
281         return new Short(s);
282     }
283 
284     /**
285      * Decodes a {@code String} into a {@code Short}.
286      * Accepts decimal, hexadecimal, and octal numbers given by
287      * the following grammar:
288      *
289      * <blockquote>
290      * <dl>
291      * <dt><i>DecodableString:</i>
292      * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
293      * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
294      * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
295      * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
296      * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
297      *
298      * <dt><i>Sign:</i>
299      * <dd>{@code -}

  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.lang;
 27 
 28 import jdk.internal.misc.CDS;
 29 import jdk.internal.misc.PreviewFeatures;
 30 import jdk.internal.value.DeserializeConstructor;
 31 import jdk.internal.vm.annotation.IntrinsicCandidate;
 32 import jdk.internal.vm.annotation.Stable;
 33 
 34 import java.lang.constant.Constable;
 35 import java.lang.constant.DynamicConstantDesc;
 36 import java.util.Optional;
 37 
 38 import static java.lang.constant.ConstantDescs.BSM_EXPLICIT_CAST;

 39 import static java.lang.constant.ConstantDescs.CD_short;
 40 import static java.lang.constant.ConstantDescs.DEFAULT_NAME;
 41 
 42 /**
 43  * The {@code Short} class is the {@linkplain
 44  * java.lang##wrapperClass wrapper class} for values of the primitive
 45  * type {@code short}. An object of type {@code Short} contains a
 46  * single field whose type is {@code short}.
 47  *
 48  * <p>In addition, this class provides several methods for converting
 49  * a {@code short} to a {@code String} and a {@code String} to a
 50  * {@code short}, as well as other constants and methods useful when
 51  * dealing with a {@code short}.
 52  *
 53  * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 54  * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
 55  * as interchangeable and should not use instances for synchronization, mutexes, or
 56  * with {@linkplain java.lang.ref.Reference object references}.
 57  *
 58  * <div class="preview-block">
 59  *      <div class="preview-comment">
 60  *          When preview features are enabled, {@code Short} is a {@linkplain Class#isValue value class}.
 61  *          Use of value class instances for synchronization, mutexes, or with
 62  *          {@linkplain java.lang.ref.Reference object references} result in
 63  *          {@link IdentityException}.
 64  *      </div>
 65  * </div>
 66  *
 67  * @see     java.lang.Number
 68  * @since   1.1
 69  */
 70 @jdk.internal.MigratedValueClass
 71 @jdk.internal.ValueBased
 72 public final class Short extends Number implements Comparable<Short>, Constable {
 73 
 74     /**
 75      * A constant holding the minimum value a {@code short} can
 76      * have, -2<sup>15</sup>.
 77      */
 78     public static final short   MIN_VALUE = -32768;
 79 
 80     /**
 81      * A constant holding the maximum value a {@code short} can
 82      * have, 2<sup>15</sup>-1.
 83      */
 84     public static final short   MAX_VALUE = 32767;
 85 
 86     /**
 87      * The {@code Class} instance representing the primitive type
 88      * {@code short}.
 89      */
 90     public static final Class<Short> TYPE = Class.getPrimitiveClass("short");

251             int size = -(-128) + 127 + 1;
252 
253             // Load and use the archived cache if it exists
254             CDS.initializeFromArchive(ShortCache.class);
255             if (archivedCache == null) {
256                 Short[] c = new Short[size];
257                 short value = -128;
258                 for(int i = 0; i < size; i++) {
259                     c[i] = new Short(value++);
260                 }
261                 archivedCache = c;
262             }
263             cache = archivedCache;
264             assert cache.length == size;
265         }
266     }
267 
268     /**
269      * Returns a {@code Short} instance representing the specified
270      * {@code short} value.
271      * <div class="preview-block">
272      *      <div class="preview-comment">
273      *          <p>
274      *              - When preview features are NOT enabled, {@code Short} is an identity class.
275      *              If a new {@code Short} instance is not required, this method
276      *              should generally be used in preference to the constructor
277      *              {@link #Short(short)}, as this method is likely to yield
278      *              significantly better space and time performance by caching
279      *              frequently requested values.
280      *              This method will always cache values in the range -128 to 127,
281      *              inclusive, and may cache other values outside of this range.
282      *          </p>
283      *          <p>
284      *              - When preview features are enabled, {@code Short} is a {@linkplain Class#isValue value class}.
285      *              The {@code valueOf} behavior is the same as invoking the constructor,
286      *              whether cached or not.
287      *          </p>
288      *      </div>
289      * </div>
290      *
291      * @param  s a short value.
292      * @return a {@code Short} instance representing {@code s}.
293      * @since  1.5
294      */
295     @IntrinsicCandidate
296     @DeserializeConstructor
297     public static Short valueOf(short s) {
298         if (!PreviewFeatures.isEnabled()) {
299             final int offset = 128;
300             int sAsInt = s;
301             if (sAsInt >= -128 && sAsInt <= 127) { // must cache
302                 return ShortCache.cache[sAsInt + offset];
303             }
304         }
305         return new Short(s);
306     }
307 
308     /**
309      * Decodes a {@code String} into a {@code Short}.
310      * Accepts decimal, hexadecimal, and octal numbers given by
311      * the following grammar:
312      *
313      * <blockquote>
314      * <dl>
315      * <dt><i>DecodableString:</i>
316      * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
317      * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
318      * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
319      * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
320      * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
321      *
322      * <dt><i>Sign:</i>
323      * <dd>{@code -}
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