org.apache.commons.lang.ClassUtils Maven / Gradle / Ivy
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/*
* Copyright 2002-2005 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.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/**
* Operates on classes without using reflection.
*
* This class handles invalid null inputs as best it can.
* Each method documents its behaviour in more detail.
*
* @author Stephen Colebourne
* @author Gary Gregory
* @author Norm Deane
* @since 2.0
* @version $Id: ClassUtils.java 161243 2005-04-14 04:30:28Z ggregory $
*/
public class ClassUtils {
/**
* The package separator character: '.' == {@value}.
*/
public static final char PACKAGE_SEPARATOR_CHAR = '.';
/**
* The package separator String: ".".
*/
public static final String PACKAGE_SEPARATOR = String.valueOf(PACKAGE_SEPARATOR_CHAR);
/**
* The inner class separator character: '$' == {@value}.
*/
public static final char INNER_CLASS_SEPARATOR_CHAR = '$';
/**
* The inner class separator String: "$".
*/
public static final String INNER_CLASS_SEPARATOR = String.valueOf(INNER_CLASS_SEPARATOR_CHAR);
/**
* Maps primitive Classes to their corresponding wrapper Class.
*/
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);
}
/**
* ClassUtils instances should NOT be constructed in standard programming.
* Instead, the class should be used as
* ClassUtils.getShortClassName(cls).
*
* This constructor is public to permit tools that require a JavaBean
* instance to operate.
*/
public ClassUtils() {
}
// Short class name
// ----------------------------------------------------------------------
/**
* Gets the class name minus the package name for an Object.
*
* @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());
}
/**
* Gets the class name minus the package name from a Class.
*
* @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());
}
/**
* Gets the class name minus the package name from a String.
*
* The string passed in is assumed to be a class name - it is not checked.
*
* @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
// ----------------------------------------------------------------------
/**
* Gets the package name of an Object.
*
* @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());
}
/**
* Gets the package name of a Class.
*
* @param cls the class to get the package name for, may be null.
* @return the package name or an empty string
*/
public static String getPackageName(Class cls) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getPackageName(cls.getName());
}
/**
* Gets the package name from a String.
*
* The string passed in is assumed to be a class name - it is not checked.
* If the class is unpackaged, return an empty string.
*
* @param className the className to get the package name for, may be null
* @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
// ----------------------------------------------------------------------
/**
* Gets a List of superclasses for the given class.
*
* @param cls the class to look up, may be null
* @return the List of superclasses in order going up from this one
* null 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;
}
/**
* Gets a List of all interfaces implemented by the given
* class and its superclasses.
*
* 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.
*
* @param cls the class to look up, may be null
* @return the List of interfaces in order,
* null 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;
}
// Convert list
// ----------------------------------------------------------------------
/**
* Given a List of class names, this method converts them into classes.
*
* A new List is returned. If the class name cannot be found, null
* is stored in the List. If the class name in the List is
* null, null is stored in the output List.
*
* @param classNames the classNames to change
* @return a List of Class objects corresponding to the class names,
* null 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;
}
/**
* Given a List of Class objects, this method converts
* them into class names.
*
* A new List is returned. null objects will be copied into
* the returned list as null.
*
* @param classes the classes to change
* @return a List of class names corresponding to the Class objects,
* null if null input
* @throws ClassCastException if classes contains a non-Class 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
// ----------------------------------------------------------------------
/**
* Checks if an array of Classes can be assigned to another array of Classes.
*
* 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).
*
* Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this
* method takes into account widenings of primitive classes and
* nulls.
*
* Primitive widenings allow an int to be assigned to a long,
* float or double. This method returns the correct
* result for these cases.
*
* Null may be assigned to any reference type. This method will
* return true if null is passed in and the toClass is
* non-primitive.
*
* Specifically, this method tests whether the type represented by the
* specified Class parameter can be converted to the type
* represented by this Class object via an identity conversion
* widening primitive or widening reference conversion. See
* The Java Language Specification,
* sections 5.1.1, 5.1.2 and 5.1.4 for details.
*
* @param classArray the array of Classes to check, may be null
* @param toClassArray the array of Classes to try to assign into, may be null
* @return true 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;
}
/**
* Checks if one Class can be assigned to a variable of
* another Class.
*
* Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method,
* this method takes into account widenings of primitive classes and
* nulls.
*
* Primitive widenings allow an int to be assigned to a long, float or
* double. This method returns the correct result for these cases.
*
* Null may be assigned to any reference type. This method
* will return true if null is passed in and the
* toClass is non-primitive.
*
* Specifically, this method tests whether the type represented by the
* specified Class parameter can be converted to the type
* represented by this Class object via an identity conversion
* widening primitive or widening reference conversion. See
* The Java Language Specification,
* sections 5.1.1, 5.1.2 and 5.1.4 for details.
*
* @param cls the Class to check, may be null
* @param toClass the Class to try to assign into, returns false if null
* @return true 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);
}
/**
* Converts the specified primitive Class object to its corresponding
* wrapper Class object.
*
* @param cls the class to convert, may be null
* @return the wrapper class for cls or cls if
* cls is not a primitive. null if null input.
* @since 2.1
*/
public static Class primitiveToWrapper(Class cls) {
Class convertedClass = cls;
if (cls != null && cls.isPrimitive()) {
convertedClass = (Class) primitiveWrapperMap.get(cls);
}
return convertedClass;
}
/**
* Converts the specified array of primitive Class objects to an array of
* its corresponding wrapper Class objects.
*
* @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. null if null input.
* Empty array if an empty array passed in.
* @since 2.1
*/
public static Class[] primitivesToWrappers(Class[] classes) {
if (classes == null) {
return null;
}
if (classes.length == 0) {
return classes;
}
Class[] convertedClasses = new Class[classes.length];
for (int i=0; i < classes.length; i++) {
convertedClasses[i] = primitiveToWrapper( classes[i] );
}
return convertedClasses;
}
// Inner class
// ----------------------------------------------------------------------
/**
* Is the specified class an inner class or static nested class.
*
* @param cls the class to check, may be null
* @return true if the class is an inner or static nested class,
* false if not or null
*/
public static boolean isInnerClass(Class cls) {
if (cls == null) {
return false;
}
return cls.getName().indexOf(INNER_CLASS_SEPARATOR_CHAR) >= 0;
}
}