< prev index next > src/java.base/share/classes/java/lang/Short.java
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*/
package java.lang;
import jdk.internal.misc.CDS;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import jdk.internal.vm.annotation.Stable;
import java.lang.constant.Constable;
import java.lang.constant.DynamicConstantDesc;
import java.util.Optional;
import static java.lang.constant.ConstantDescs.BSM_EXPLICIT_CAST;
- import static java.lang.constant.ConstantDescs.CD_int;
import static java.lang.constant.ConstantDescs.CD_short;
import static java.lang.constant.ConstantDescs.DEFAULT_NAME;
/**
* The {@code Short} class is the {@linkplain
*/
package java.lang;
import jdk.internal.misc.CDS;
+ import jdk.internal.misc.PreviewFeatures;
+ import jdk.internal.value.DeserializeConstructor;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import jdk.internal.vm.annotation.Stable;
import java.lang.constant.Constable;
import java.lang.constant.DynamicConstantDesc;
import java.util.Optional;
import static java.lang.constant.ConstantDescs.BSM_EXPLICIT_CAST;
import static java.lang.constant.ConstantDescs.CD_short;
import static java.lang.constant.ConstantDescs.DEFAULT_NAME;
/**
* The {@code Short} class is the {@linkplain
* a {@code short} to a {@code String} and a {@code String} to a
* {@code short}, as well as other constants and methods useful when
* dealing with a {@code short}.
*
* <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
! * class; programmers should treat instances that are
! * {@linkplain #equals(Object) equal} as interchangeable and should not
! * use instances for synchronization, or unpredictable behavior may
! * occur. For example, in a future release, synchronization may fail.
*
* @author Nakul Saraiya
* @author Joseph D. Darcy
* @see java.lang.Number
* @since 1.1
*/
@jdk.internal.ValueBased
public final class Short extends Number implements Comparable<Short>, Constable {
/**
* A constant holding the minimum value a {@code short} can
* a {@code short} to a {@code String} and a {@code String} to a
* {@code short}, as well as other constants and methods useful when
* dealing with a {@code short}.
*
* <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
! * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
! * as interchangeable and should not use instances for synchronization, mutexes, or
! * with {@linkplain java.lang.ref.Reference object references}.
! *
+ * <div class="preview-block">
+ * <div class="preview-comment">
+ * When preview features are enabled, {@code Short} is a {@linkplain Class#isValue value class}.
+ * Use of value class instances for synchronization, mutexes, or with
+ * {@linkplain java.lang.ref.Reference object references} result in
+ * {@link IdentityException}.
+ * </div>
+ * </div>
*
* @author Nakul Saraiya
* @author Joseph D. Darcy
* @see java.lang.Number
* @since 1.1
*/
+ @jdk.internal.MigratedValueClass
@jdk.internal.ValueBased
public final class Short extends Number implements Comparable<Short>, Constable {
/**
* A constant holding the minimum value a {@code short} can
}
/**
* Returns a {@code Short} instance representing the specified
* {@code short} value.
! * If a new {@code Short} instance is not required, this method
! * should generally be used in preference to the constructor
! * {@link #Short(short)}, as this method is likely to yield
! * significantly better space and time performance by caching
! * frequently requested values.
! *
! * This method will always cache values in the range -128 to 127,
! * inclusive, and may cache other values outside of this range.
*
* @param s a short value.
* @return a {@code Short} instance representing {@code s}.
* @since 1.5
*/
@IntrinsicCandidate
public static Short valueOf(short s) {
! final int offset = 128;
! int sAsInt = s;
! if (sAsInt >= -128 && sAsInt <= 127) { // must cache
! return ShortCache.cache[sAsInt + offset];
}
return new Short(s);
}
/**
}
/**
* Returns a {@code Short} instance representing the specified
* {@code short} value.
! * <div class="preview-block">
! * <div class="preview-comment">
! * <p>
! * - When preview features are NOT enabled, {@code Short} is an identity class.
! * If a new {@code Short} instance is not required, this method
! * should generally be used in preference to the constructor
! * {@link #Short(short)}, as this method is likely to yield
! * significantly better space and time performance by caching
+ * frequently requested values.
+ * This method will always cache values in the range -128 to 127,
+ * inclusive, and may cache other values outside of this range.
+ * </p>
+ * <p>
+ * - When preview features are enabled, {@code Short} is a {@linkplain Class#isValue value class}.
+ * The {@code valueOf} behavior is the same as invoking the constructor,
+ * whether cached or not.
+ * </p>
+ * </div>
+ * </div>
*
* @param s a short value.
* @return a {@code Short} instance representing {@code s}.
* @since 1.5
*/
@IntrinsicCandidate
+ @DeserializeConstructor
public static Short valueOf(short s) {
! if (!PreviewFeatures.isEnabled()) {
! final int offset = 128;
! int sAsInt = s;
! if (sAsInt >= -128 && sAsInt <= 127) { // must cache
+ return ShortCache.cache[sAsInt + offset];
+ }
}
return new Short(s);
}
/**
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