/*
* JBoss, Home of Professional Open Source
* Copyright 2011, Red Hat, Inc. and/or its affiliates, and individual
* contributors by the @authors tag. See the copyright.txt in the
* distribution for a full listing of individual contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.solder.reflection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
/**
* Contains static utility methods for boxing and unboxing primitive types and
* their corresponding wrapper types.
* <p/>
* <p>
* Adopted from the <a href=
* "http://guava-libraries.googlecode.com/svn-history/r144/tags/release07/src/com/google/common/primitives/Primitives.java"
* >Primitives</a> class in the Guava libraries project.
* </p>
*
* @author Kevin Bourrillion
*/
public final class PrimitiveTypes {
private PrimitiveTypes() {
}
/**
* A map from primitive types to their corresponding wrapper types.
*/
private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPE;
/**
* A map from wrapper types to their corresponding primitive types.
*/
private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPE;
// Sad that we can't use a BiMap. :(
static {
Map<Class<?>, Class<?>> primToWrap = new HashMap<Class<?>, Class<?>>(16);
Map<Class<?>, Class<?>> wrapToPrim = new HashMap<Class<?>, Class<?>>(16);
add(primToWrap, wrapToPrim, boolean.class, Boolean.class);
add(primToWrap, wrapToPrim, byte.class, Byte.class);
add(primToWrap, wrapToPrim, char.class, Character.class);
add(primToWrap, wrapToPrim, double.class, Double.class);
add(primToWrap, wrapToPrim, float.class, Float.class);
add(primToWrap, wrapToPrim, int.class, Integer.class);
add(primToWrap, wrapToPrim, long.class, Long.class);
add(primToWrap, wrapToPrim, short.class, Short.class);
add(primToWrap, wrapToPrim, void.class, Void.class);
PRIMITIVE_TO_WRAPPER_TYPE = Collections.unmodifiableMap(primToWrap);
WRAPPER_TO_PRIMITIVE_TYPE = Collections.unmodifiableMap(wrapToPrim);
}
private static void add(Map<Class<?>, Class<?>> forward,
Map<Class<?>, Class<?>> backward, Class<?> key, Class<?> value) {
forward.put(key, value);
backward.put(value, key);
}
/**
* Returns an immutable set of all nine primitive types (including {@code
* void}). Note that a simpler way to test whether a {@code Class} instance
* is a member of this set is to call {@link Class#isPrimitive}.
*/
public static Set<Class<?>> allPrimitiveTypes() {
return PRIMITIVE_TO_WRAPPER_TYPE.keySet();
}
/**
* Returns an immutable set of all nine primitive-wrapper types (including
* {@link Void}).
*/
public static Set<Class<?>> allWrapperTypes() {
return WRAPPER_TO_PRIMITIVE_TYPE.keySet();
}
/**
* Returns {@code true} if {@code type} is one of the nine
* primitive-wrapper types, such as {@link Integer}. This
* complements the JDK method {@link Class#isPrimitive()}.
*
* @see Class#isPrimitive
*/
public static boolean isWrapperType(Class<?> type) {
return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(checkNotNull(type));
}
/**
* Returns the corresponding wrapper type of {@code type} if it is a primitive
* type; otherwise returns {@code type} itself. Idempotent.
* <pre>
* box(int.class) == Integer.class
* box(Integer.class) == Integer.class
* box(String.class) == String.class
* </pre>
*/
public static <T> Class<T> box(Class<T> type) {
checkNotNull(type);
// cast is safe: long.class and Long.class are both of type Class<Long>
@SuppressWarnings("unchecked")
Class<T> boxed = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(type);
return (boxed == null) ? type : boxed;
}
/**
* Returns the corresponding primitive type of {@code type} if it is a
* wrapper type; otherwise returns {@code type} itself. Idempotent.
* <pre>
* unbox(Integer.class) == int.class
* unbox(int.class) == int.class
* unbox(String.class) == String.class
* </pre>
*/
public static <T> Class<T> unbox(Class<T> type) {
checkNotNull(type);
// cast is safe: long.class and Long.class are both of type Class<Long>
@SuppressWarnings("unchecked")
Class<T> unboxed = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(type);
return (unboxed == null) ? type : unboxed;
}
private static <T> T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
}