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6361826: (reflect) provide method for mapping strings to class object for primitive types

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Reviewed-by: rriggs, mchung
This commit is contained in:
Joe Darcy 2023-07-14 20:18:23 +00:00
parent c84866ac0d
commit 19691fab48
3 changed files with 142 additions and 16 deletions
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17
src/java.base/share/classes/java/io/ObjectInputStream.java
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@ -261,21 +261,6 @@ public class ObjectInputStream
/** marker for unshared objects in internal handle table */
private static final Object unsharedMarker = new Object();
/**
* immutable table mapping primitive type names to corresponding
* class objects
*/
private static final Map<String, Class<?>> primClasses =
Map.of("boolean", boolean.class,
"byte", byte.class,
"char", char.class,
"short", short.class,
"int", int.class,
"long", long.class,
"float", float.class,
"double", double.class,
"void", void.class);
private static class Caches {
/** cache of subclass security audit results */
static final ClassValue<Boolean> subclassAudits =
@ -803,7 +788,7 @@ public class ObjectInputStream
try {
return Class.forName(name, false, latestUserDefinedLoader());
} catch (ClassNotFoundException ex) {
Class<?> cl = primClasses.get(name);
Class<?> cl = Class.forPrimitiveName(name);
if (cl != null) {
return cl;
} else {

38
src/java.base/share/classes/java/lang/Class.java
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@ -438,6 +438,9 @@ 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 +631,41 @@ 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}

103
test/jdk/java/lang/Class/ForPrimitiveName.java Normal file
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@ -0,0 +1,103 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @summary Test Class.forPrimitiveName
* @bug 6361826
*/
import java.util.*;
public class ForPrimitiveName {
public static void main(String... args) {
positiveTests();
negativeTests();
}
private static final void positiveTests() {
/**
* immutable table mapping primitive type names to corresponding
* class objects
*/
final Map<String, Class<?>> primClasses =
Map.of("boolean", boolean.class,
"byte", byte.class,
"char", char.class,
"short", short.class,
"int", int.class,
"long", long.class,
"float", float.class,
"double", double.class,
"void", void.class);
for (var entry : primClasses.entrySet()) {
String key = entry.getKey();
Class<?> expected = entry.getValue();
Class<?> result = Class.forPrimitiveName(key);
// For java.lang.Class, equality is identity.
if (result != expected) {
throw new RuntimeException("Unexpected mapping for " + key);
}
}
}
private static final void negativeTests() {
final List<String> expectedNull =
List.of("java.lang.Object",
"java.lang.String",
// descriptor string names for primitive types
"Z", // boolean
"B", // byte
"C", // char
"D", // double
"F", // float
"I", // int
"L", // long
"S", // short
"V", // void
// Wrapper classes
"java.lang.Byte",
"java.lang.Boolean",
"java.lang.Character",
"java.lang.Short",
"java.lang.Integer",
"java.lang.Long",
"java.lang.Float",
"java.lang.Double",
"java.lang.Void");
for (var entry : expectedNull) {
Class<?> result = Class.forPrimitiveName(entry);
if (result != null ) {
throw new RuntimeException("Unexpected nonnull result for " +
entry);
}
}
}
}