/*
* Copyright 2002-2004 The Apache Software Foundation.
*
* 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.apache.commons.lang;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/**
* <p>Operates on classes without using reflection.</p>
*
* <p>This class handles invalid <code>null</code> inputs as best it can.
* Each method documents its behaviour in more detail.</p>
*
* @author Stephen Colebourne
* @author Gary Gregory
* @author Norm Deane
* @since 2.0
* @version $Id: ClassUtils.java,v 1.30 2004/06/30 18:33:58 ggregory Exp $
*/
public class ClassUtils {
/**
* <p>The package separator character: <code>'.' == {@value}</code>.</p>
*/
public static final char PACKAGE_SEPARATOR_CHAR = '.';
/**
* <p>The package separator String: <code>"."</code>.</p>
*/
public static final String PACKAGE_SEPARATOR = String.valueOf(PACKAGE_SEPARATOR_CHAR);
/**
* <p>The inner class separator character: <code>'$' == {@value}</code>.</p>
*/
public static final char INNER_CLASS_SEPARATOR_CHAR = '$';
/**
* <p>The inner class separator String: <code>"$"</code>.</p>
*/
public static final String INNER_CLASS_SEPARATOR = String.valueOf(INNER_CLASS_SEPARATOR_CHAR);
/**
* Maps primitive <code>Class</code>es to their corresponding wrapper <code>Class</code>.
*/
private static Map primitiveWrapperMap = new HashMap();
static {
primitiveWrapperMap.put(Boolean.TYPE, Boolean.class);
primitiveWrapperMap.put(Byte.TYPE, Byte.class);
primitiveWrapperMap.put(Character.TYPE, Character.class);
primitiveWrapperMap.put(Short.TYPE, Short.class);
primitiveWrapperMap.put(Integer.TYPE, Integer.class);
primitiveWrapperMap.put(Long.TYPE, Long.class);
primitiveWrapperMap.put(Double.TYPE, Double.class);
primitiveWrapperMap.put(Float.TYPE, Float.class);
}
/**
* <p>ClassUtils instances should NOT be constructed in standard programming.
* Instead, the class should be used as
* <code>ClassUtils.getShortClassName(cls)</code>.</p>
*
* <p>This constructor is public to permit tools that require a JavaBean
* instance to operate.</p>
*/
public ClassUtils() {
}
// Short class name
// ----------------------------------------------------------------------
/**
* <p>Gets the class name minus the package name for an <code>Object</code>.</p>
*
* @param object the class to get the short name for, may be null
* @param valueIfNull the value to return if null
* @return the class name of the object without the package name, or the null value
*/
public static String getShortClassName(Object object, String valueIfNull) {
if (object == null) {
return valueIfNull;
}
return getShortClassName(object.getClass().getName());
}
/**
* <p>Gets the class name minus the package name from a <code>Class</code>.</p>
*
* @param cls the class to get the short name for.
* @return the class name without the package name or an empty string
*/
public static String getShortClassName(Class cls) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getShortClassName(cls.getName());
}
/**
* <p>Gets the class name minus the package name from a String.</p>
*
* <p>The string passed in is assumed to be a class name - it is not checked.</p>
*
* @param className the className to get the short name for
* @return the class name of the class without the package name or an empty string
*/
public static String getShortClassName(String className) {
if (className == null) {
return StringUtils.EMPTY;
}
if (className.length() == 0) {
return StringUtils.EMPTY;
}
char[] chars = className.toCharArray();
int lastDot = 0;
for (int i = 0; i < chars.length; i++) {
if (chars[i] == PACKAGE_SEPARATOR_CHAR) {
lastDot = i + 1;
} else if (chars[i] == INNER_CLASS_SEPARATOR_CHAR) { // handle inner classes
chars[i] = PACKAGE_SEPARATOR_CHAR;
}
}
return new String(chars, lastDot, chars.length - lastDot);
}
// Package name
// ----------------------------------------------------------------------
/**
* <p>Gets the package name of an <code>Object</code>.</p>
*
* @param object the class to get the package name for, may be null
* @param valueIfNull the value to return if null
* @return the package name of the object, or the null value
*/
public static String getPackageName(Object object, String valueIfNull) {
if (object == null) {
return valueIfNull;
}
return getPackageName(object.getClass().getName());
}
/**
* <p>Gets the package name of a <code>Class</code>.</p>
*
* @param cls the class to get the package name for, may be <code>null</code>.
* @return the package name or an empty string
*/
public static String getPackageName(Class cls) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getPackageName(cls.getName());
}
/**
* <p>Gets the package name from a <code>String</code>.</p>
*
* <p>The string passed in is assumed to be a class name - it is not checked.</p>
* <p>If the class is unpackaged, return an empty string.</p>
*
* @param className the className to get the package name for, may be <code>null</code>
* @return the package name or an empty string
*/
public static String getPackageName(String className) {
if (className == null) {
return StringUtils.EMPTY;
}
int i = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (i == -1) {
return StringUtils.EMPTY;
}
return className.substring(0, i);
}
// Superclasses/Superinterfaces
// ----------------------------------------------------------------------
/**
* <p>Gets a <code>List</code> of superclasses for the given class.</p>
*
* @param cls the class to look up, may be <code>null</code>
* @return the <code>List</code> of superclasses in order going up from this one
* <code>null</code> if null input
*/
public static List getAllSuperclasses(Class cls) {
if (cls == null) {
return null;
}
List classes = new ArrayList();
Class superclass = cls.getSuperclass();
while (superclass != null) {
classes.add(superclass);
superclass = superclass.getSuperclass();
}
return classes;
}
/**
* <p>Gets a <code>List</code> of all interfaces implemented by the given
* class and its superclasses.</p>
*
* <p>The order is determined by looking through each interface in turn as
* declared in the source file and following its hierarchy up. Then each
* superclass is considered in the same way. Later duplicates are ignored,
* so the order is maintained.</p>
*
* @param cls the class to look up, may be <code>null</code>
* @return the <code>List</code> of interfaces in order,
* <code>null</code> if null input
*/
public static List getAllInterfaces(Class cls) {
if (cls == null) {
return null;
}
List list = new ArrayList();
while (cls != null) {
Class[] interfaces = cls.getInterfaces();
for (int i = 0; i < interfaces.length; i++) {
if (list.contains(interfaces[i]) == false) {
list.add(interfaces[i]);
}
List superInterfaces = getAllInterfaces(interfaces[i]);
for (Iterator it = superInterfaces.iterator(); it.hasNext();) {
Class intface = (Class) it.next();
if (list.contains(intface) == false) {
list.add(intface);
}
}
}
cls = cls.getSuperclass();
}
return list;
}
// /**
// * <p>Gets a <code>List</code> of subclasses of the specified class.</p>
// *
// * <p>This method searches the classpath to find all the subclasses
// * of a particular class available. No classes are loaded, the
// * returned list contains class names, not classes.</p>
// *
// * @param cls the class to find subclasses for
// * @return the <code>List</code> of subclass String class names
// * @throws IllegalArgumentException if the class is <code>null</code>
// */
// public static List getAllSubclassNames(Class cls) {
// if (cls == null) {
// throw new IllegalArgumentException("The class must not be null");
// }
// // TODO Use JavaWorld tip for searching the classpath
// return null;
// }
// /**
// * <p>Gets a <code>List</code> of subclasses of the specified class.</p>
// *
// * <p>This method searches the classpath to find all the subclasses
// * of a particular class available.</p>
// *
// * @param cls the class to find subclasses for
// * @return the <code>List</code> of subclasses
// * @throws IllegalArgumentException if the class is <code>null</code>
// */
// public static List getAllSubclasses(Class cls) {
// List names = getAllSubclassNames(cls);
// return convertClassNamesToClasses(names);
// }
// /**
// * <p>Gets a <code>List</code> of implementations of the specified interface.</p>
// *
// * <p>This method searches the classpath to find all the implementations
// * of a particular interface available. No classes are loaded, the
// * returned list contains class names, not classes.</p>
// *
// * @param cls the class to find sub classes for
// * @return the <code>List</code> of implementation String class names
// * @throws IllegalArgumentException if the class is <code>null</code>
// */
// public static List getAllImplementationClassNames(Class cls) {
// if (cls == null) {
// throw new IllegalArgumentException("The class must not be null");
// }
// // TODO Use JavaWorld tip for searching the classpath
// return null;
// }
// Convert list
// ----------------------------------------------------------------------
/**
* <p>Given a <code>List</code> of class names, this method converts them into classes.</p>
*
* <p>A new <code>List</code> is returned. If the class name cannot be found, <code>null</code>
* is stored in the <code>List</code>. If the class name in the <code>List</code> is
* <code>null</code>, <code>null</code> is stored in the output <code>List</code>.</p>
*
* @param classNames the classNames to change
* @return a <code>List</code> of Class objects corresponding to the class names,
* <code>null</code> if null input
* @throws ClassCastException if classNames contains a non String entry
*/
public static List convertClassNamesToClasses(List classNames) {
if (classNames == null) {
return null;
}
List classes = new ArrayList(classNames.size());
for (Iterator it = classNames.iterator(); it.hasNext();) {
String className = (String) it.next();
try {
classes.add(Class.forName(className));
} catch (Exception ex) {
classes.add(null);
}
}
return classes;
}
/**
* <p>Given a <code>List</code> of <code>Class</code> objects, this method converts
* them into class names.</p>
*
* <p>A new <code>List</code> is returned. <code>null</code> objects will be copied into
* the returned list as <code>null</code>.</p>
*
* @param classes the classes to change
* @return a <code>List</code> of class names corresponding to the Class objects,
* <code>null</code> if null input
* @throws ClassCastException if <code>classes</code> contains a non-<code>Class</code> entry
*/
public static List convertClassesToClassNames(List classes) {
if (classes == null) {
return null;
}
List classNames = new ArrayList(classes.size());
for (Iterator it = classes.iterator(); it.hasNext();) {
Class cls = (Class) it.next();
if (cls == null) {
classNames.add(null);
} else {
classNames.add(cls.getName());
}
}
return classNames;
}
// Is assignable
// ----------------------------------------------------------------------
/**
* <p>Checks if an array of Classes can be assigned to another array of Classes.</p>
*
* <p>This method calls {@link #isAssignable(Class, Class) isAssignable} for each
* Class pair in the input arrays. It can be used to check if a set of arguments
* (the first parameter) are suitably compatible with a set of method parameter types
* (the second parameter).</p>
*
* <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this
* method takes into account widenings of primitive classes and
* <code>null</code>s.</p>
*
* <p>Primitive widenings allow an int to be assigned to a <code>long</code>,
* <code>float</code> or <code>double</code>. This method returns the correct
* result for these cases.</p>
*
* <p><code>Null</code> may be assigned to any reference type. This method will
* return <code>true</code> if <code>null</code> is passed in and the toClass is
* non-primitive.</p>
*
* <p>Specifically, this method tests whether the type represented by the
* specified <code>Class</code> parameter can be converted to the type
* represented by this <code>Class</code> object via an identity conversion
* widening primitive or widening reference conversion. See
* <em><a href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>,
* sections 5.1.1, 5.1.2 and 5.1.4 for details.</p>
*
* @param classArray the array of Classes to check, may be <code>null</code>
* @param toClassArray the array of Classes to try to assign into, may be <code>null</code>
* @return <code>true</code> if assignment possible
*/
public static boolean isAssignable(Class[] classArray, Class[] toClassArray) {
if (ArrayUtils.isSameLength(classArray, toClassArray) == false) {
return false;
}
if (classArray == null) {
classArray = ArrayUtils.EMPTY_CLASS_ARRAY;
}
if (toClassArray == null) {
toClassArray = ArrayUtils.EMPTY_CLASS_ARRAY;
}
for (int i = 0; i < classArray.length; i++) {
if (isAssignable(classArray[i], toClassArray[i]) == false) {
return false;
}
}
return true;
}
/**
* <p>Checks if one <code>Class</code> can be assigned to a variable of
* another <code>Class</code>.</p>
*
* <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method,
* this method takes into account widenings of primitive classes and
* <code>null</code>s.</p>
*
* <p>Primitive widenings allow an int to be assigned to a long, float or
* double. This method returns the correct result for these cases.</p>
*
* <p><code>Null</code> may be assigned to any reference type. This method
* will return <code>true</code> if <code>null</code> is passed in and the
* toClass is non-primitive.</p>
*
* <p>Specifically, this method tests whether the type represented by the
* specified <code>Class</code> parameter can be converted to the type
* represented by this <code>Class</code> object via an identity conversion
* widening primitive or widening reference conversion. See
* <em><a href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>,
* sections 5.1.1, 5.1.2 and 5.1.4 for details.</p>
*
* @param cls the Class to check, may be null
* @param toClass the Class to try to assign into, returns false if null
* @return <code>true</code> if assignment possible
*/
public static boolean isAssignable(Class cls, Class toClass) {
if (toClass == null) {
return false;
}
// have to check for null, as isAssignableFrom doesn't
if (cls == null) {
return !(toClass.isPrimitive());
}
if (cls.equals(toClass)) {
return true;
}
if (cls.isPrimitive()) {
if (toClass.isPrimitive() == false) {
return false;
}
if (Integer.TYPE.equals(cls)) {
return Long.TYPE.equals(toClass)
|| Float.TYPE.equals(toClass)
|| Double.TYPE.equals(toClass);
}
if (Long.TYPE.equals(cls)) {
return Float.TYPE.equals(toClass)
|| Double.TYPE.equals(toClass);
}
if (Boolean.TYPE.equals(cls)) {
return false;
}
if (Double.TYPE.equals(cls)) {
return false;
}
if (Float.TYPE.equals(cls)) {
return Double.TYPE.equals(toClass);
}
if (Character.TYPE.equals(cls)) {
return Integer.TYPE.equals(toClass)
|| Long.TYPE.equals(toClass)
|| Float.TYPE.equals(toClass)
|| Double.TYPE.equals(toClass);
}
if (Short.TYPE.equals(cls)) {
return Integer.TYPE.equals(toClass)
|| Long.TYPE.equals(toClass)
|| Float.TYPE.equals(toClass)
|| Double.TYPE.equals(toClass);
}
if (Byte.TYPE.equals(cls)) {
return Short.TYPE.equals(toClass)
|| Integer.TYPE.equals(toClass)
|| Long.TYPE.equals(toClass)
|| Float.TYPE.equals(toClass)
|| Double.TYPE.equals(toClass);
}
// should never get here
return false;
}
return toClass.isAssignableFrom(cls);
}
/**
* <p>Converts the specified primitive Class object to its corresponding
* wrapper Class object.</p>
*
* @param cls the class to convert, may be null
* @return the wrapper class for <code>cls</code> or <code>cls</code> if
* <code>cls</code> is not a primitive. <code>null</code> if null input.
*/
public static Class primitiveToWrapper(Class cls) {
Class convertedClass = cls;
if (cls != null && cls.isPrimitive()) {
convertedClass = (Class) primitiveWrapperMap.get(cls);
}
return convertedClass;
}
/**
* <p>Converts the specified array of primitive Class objects to an array of
* its corresponding wrapper Class objects.</p>
*
* @param classes the class array to convert, may be null or empty
* @return an array which contains for each given class, the wrapper class or
* the original class if class is not a primitive. <code>null</code> if null input.
* Empty array if an empty array passed in.
*/
public static Class[] primitivesToWrappers(Class[] classes) {
if (classes == null) {
return null;
}
if (classes.length == 0) {
return ArrayUtils.EMPTY_CLASS_ARRAY;
}
Class[] convertedClasses = new Class[classes.length];
for (int i=0; i < classes.length; i++) {
convertedClasses[i] = primitiveToWrapper( classes[i] );
}
return convertedClasses;
}
// Inner class
// ----------------------------------------------------------------------
/**
* <p>Is the specified class an inner class or static nested class.</p>
*
* @param cls the class to check, may be null
* @return <code>true</code> if the class is an inner or static nested class,
* false if not or <code>null</code>
*/
public static boolean isInnerClass(Class cls) {
if (cls == null) {
return false;
}
return (cls.getName().indexOf(INNER_CLASS_SEPARATOR_CHAR) >= 0);
}
//-----------------------------------------------------------------------
/**
* Compares two <code>Class</code>s by name.
*/
private static class ClassNameComparator implements Comparator {
/**
* Compares two <code>Class</code>s by name.
*
* @throws ClassCastException
* If <code>o1</code> or <code>o2</code> are not <code>Class</code>
* instances.
*/
public int compare(Object o1, Object o2) {
Class class1 = (Class) o1;
Class class2 = (Class) o2;
if (class1 == null) {
return class2 == null ? 0 : -1;
}
if (class2 == null) {
return 1;
}
return class1.getName().compareTo(class2.getName());
}
}
/**
* Compares two <code>Class</code>s by name.
*/
public static final Comparator CLASS_NAME_COMPARATOR = new ClassNameComparator();
/**
* Compares two <code>Package</code>s by name.
*/
private static class PackageNameComparator implements Comparator {
/**
* Compares two <code>Package</code>s by name.
*
* @throws ClassCastException
* If <code>o1</code> or <code>o2</code> are not <code>Package</code>
* instances.
*/
public int compare(Object o1, Object o2) {
Package package1 = (Package) o1;
Package package2 = (Package) o2;
if (package1 == null) {
return package2 == null ? 0 : -1;
}
if (package2 == null) {
return 1;
}
return package1.getName().compareTo(package2.getName());
}
}
/**
* Compares two <code>Package</code>s by name.
*/
public static final Comparator PACKAGE_NAME_COMPARATOR = new PackageNameComparator();
}
