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

@@ -31,10 +31,11 @@
  import java.util.Optional;
  
  import jdk.internal.math.FloatingDecimal;
  import jdk.internal.math.DoubleConsts;
  import jdk.internal.math.DoubleToDecimal;
+ import jdk.internal.value.DeserializeConstructor;
  import jdk.internal.vm.annotation.IntrinsicCandidate;
  
  /**
   * The {@code Double} class is the {@linkplain
   * java.lang##wrapperClass wrapper class} for values of the primitive

@@ -46,14 +47,22 @@
   * {@code String} to a {@code double}, as well as other
   * constants and methods useful when dealing with a
   * {@code double}.
   *
   * <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.
+  * 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 Double} 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>
   *
   * <h2><a id=equivalenceRelation>Floating-point Equality, Equivalence,
   * and Comparison</a></h2>
   *
   * IEEE 754 floating-point values include finite nonzero values,

@@ -355,10 +364,11 @@
   * @author  Lee Boynton
   * @author  Arthur van Hoff
   * @author  Joseph D. Darcy
   * @since 1.0
   */
+ @jdk.internal.MigratedValueClass
  @jdk.internal.ValueBased
  public final class Double extends Number
          implements Comparable<Double>, Constable, ConstantDesc {
      /**
       * A constant holding the positive infinity of type

@@ -945,10 +955,11 @@
       * @param  d a double value.
       * @return a {@code Double} instance representing {@code d}.
       * @since  1.5
       */
      @IntrinsicCandidate
+     @DeserializeConstructor
      public static Double valueOf(double d) {
          return new Double(d);
      }
  
      /**