Summary

Add the method Class.forPrimitiveName(String) to map from the name of a primitive type (int, long, etc.) to a Class object.

Problem

A long-standing gap in built-in core reflection functionality was a direct mapping from the name of a primitive type to its corresponding class object. At least one implementation of this functionality appears privately in the JDK.

Solution

Add a Class.forPrimitiveName(String) that maps "int" to int.class, "long" to long.class, etc.

Specification

--- a/src/java.base/share/classes/java/lang/Class.java
+++ b/src/java.base/share/classes/java/lang/Class.java
@@ -438,6 +438,8 @@ public final class Class<T> implements java.io.Serializable,
      * If {@code name} denotes a primitive type or void, for example {@code I},
      * an attempt will be made to locate a user-defined class in the unnamed package
      * whose name is {@code I} instead.

• * To obtain a {@code Class} object for a named primitive type
  

• * such as {@code int} or {@code long} use {@link
  

• * #forPrimitiveName(String)}.
      *
      * <p> To obtain the {@code Class} object associated with an array class,
      * the name consists of one or more {@code '['} representing the depth
  

  @@ -628,6 +630,41 @@ public final class Class<T> implements java.io.Serializable, } }

  • /**

  • * {@return the {@code Class} object associated with the
    

  • * {@linkplain #isPrimitive() primitive type} of the given name}
    

  • * If the argument is not the name of a primitive type, {@code
    

  • * null} is returned.
    

  • *
    

  • * @param primitiveName the name of the primitive type to find
    

  • *
    

  • * @throws NullPointerException if the argument is {@code null}
    

  • *
    

  • * @jls 4.2 Primitive Types and Values
    

  • * @jls 15.8.2 Class Literals
    

  • * @since 22
    

  • */
    

  • public static Class<?> forPrimitiveName(String primitiveName) {

  •    return switch(primitiveName) {
    

  •    // Integral types
    

  •    case "int"     -> int.class;
    

  •    case "long"    -> long.class;
    

  •    case "short"   -> short.class;
    

  •    case "char"    -> char.class;
    

  •    case "byte"    -> byte.class;
    

  •    // Floating-point types
    

  •    case "float"   -> float.class;
    

  •    case "double"  -> double.class;
    

  •    // Other types
    

  •    case "boolean" -> boolean.class;
    

  •    case "void"    -> void.class;
    

  •    default        -> null;
    

  •    };
    

  • }
  • /** * Creates a new instance of the class represented by this {@code Class} * object. The class is instantiated as if by a {@code new}