Operates on classes without using reflection.
* *This class handles invalid null inputs as best it can.
* Each method documents its behaviour in more detail.
The notion of a canonical name includes the human
* readable name for the type, for example int[]. The
* non-canonical method variants work with the JVM names, such as
* [I.
The package separator character: '.' == {@value}.
The package separator String: ".".
The inner class separator character: '$' == {@value}.
The inner class separator String: "$".
Classes to their corresponding wrapper Class.
*/
private static final 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);
primitiveWrapperMap.put(Void.TYPE, Void.TYPE);
}
/**
* Maps wrapper Classes to their corresponding primitive types.
*/
private static final Map wrapperPrimitiveMap = new HashMap();
static {
for (Iterator it = primitiveWrapperMap.keySet().iterator(); it.hasNext();) {
Class primitiveClass = (Class) it.next();
Class wrapperClass = (Class) primitiveWrapperMap.get(primitiveClass);
if (!primitiveClass.equals(wrapperClass)) {
wrapperPrimitiveMap.put(wrapperClass, primitiveClass);
}
}
}
/**
* Maps a primitive class name to its corresponding abbreviation used in array class names.
*/
private static final Map abbreviationMap = new HashMap();
/**
* Maps an abbreviation used in array class names to corresponding primitive class name.
*/
private static final Map reverseAbbreviationMap = new HashMap();
/**
* Add primitive type abbreviation to maps of abbreviations.
*
* @param primitive Canonical name of primitive type
* @param abbreviation Corresponding abbreviation of primitive type
*/
private static void addAbbreviation(String primitive, String abbreviation) {
abbreviationMap.put(primitive, abbreviation);
reverseAbbreviationMap.put(abbreviation, primitive);
}
/**
* Feed abbreviation maps
*/
static {
addAbbreviation("int", "I");
addAbbreviation("boolean", "Z");
addAbbreviation("float", "F");
addAbbreviation("long", "J");
addAbbreviation("short", "S");
addAbbreviation("byte", "B");
addAbbreviation("double", "D");
addAbbreviation("char", "C");
}
/**
* 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() { super(); } // Short class name // ---------------------------------------------------------------------- /** *Gets the class name minus the package name for an Object.
Gets the class name minus the package name from a Class.
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; } StrBuilder arrayPrefix = new StrBuilder(); // Handle array encoding if (className.startsWith("[")) { while (className.charAt(0) == '[') { className = className.substring(1); arrayPrefix.append("[]"); } // Strip Object type encoding if (className.charAt(0) == 'L' && className.charAt(className.length() - 1) == ';') { className = className.substring(1, className.length() - 1); } } if (reverseAbbreviationMap.containsKey(className)) { className = (String)reverseAbbreviationMap.get(className); } int lastDotIdx = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); int innerIdx = className.indexOf( INNER_CLASS_SEPARATOR_CHAR, lastDotIdx == -1 ? 0 : lastDotIdx + 1); String out = className.substring(lastDotIdx + 1); if (innerIdx != -1) { out = out.replace(INNER_CLASS_SEPARATOR_CHAR, PACKAGE_SEPARATOR_CHAR); } return out + arrayPrefix; } // Package name // ---------------------------------------------------------------------- /** *Gets the package name of an Object.
Gets the package name of a Class.
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 benull
* @return the package name or an empty string
*/
public static String getPackageName(String className) {
if (className == null || className.length() == 0) {
return StringUtils.EMPTY;
}
// Strip array encoding
while (className.charAt(0) == '[') {
className = className.substring(1);
}
// Strip Object type encoding
if (className.charAt(0) == 'L' && className.charAt(className.length() - 1) == ';') {
className = className.substring(1);
}
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.
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 benull
* @return the List of interfaces in order,
* null if null input
*/
public static List getAllInterfaces(Class cls) {
if (cls == null) {
return null;
}
List interfacesFound = new ArrayList();
getAllInterfaces(cls, interfacesFound);
return interfacesFound;
}
/**
* Get the interfaces for the specified class.
*
* @param cls the class to look up, may be null
* @param interfacesFound the Set of interfaces for the class
*/
private static void getAllInterfaces(Class cls, List interfacesFound) {
while (cls != null) {
Class[] interfaces = cls.getInterfaces();
for (int i = 0; i < interfaces.length; i++) {
if (!interfacesFound.contains(interfaces[i])) {
interfacesFound.add(interfaces[i]);
getAllInterfaces(interfaces[i], interfacesFound);
}
}
cls = cls.getSuperclass();
}
}
// 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.
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.
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.
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) {
return isAssignable(classArray, toClassArray, false);
}
/**
* 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.
null
* @param toClassArray the array of Classes to try to assign into, may be null
* @param autoboxing whether to use implicit autoboxing/unboxing between primitives and wrappers
* @return true if assignment possible
* @since 2.5
*/
public static boolean isAssignable(Class[] classArray, Class[] toClassArray, boolean autoboxing) {
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], autoboxing) == 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.
true if assignment possible
*/
public static boolean isAssignable(Class cls, Class toClass) {
return isAssignable(cls, toClass, false);
}
/**
* 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.
true if assignment possible
* @since 2.5
*/
public static boolean isAssignable(Class cls, Class toClass, boolean autoboxing) {
if (toClass == null) {
return false;
}
// have to check for null, as isAssignableFrom doesn't
if (cls == null) {
return !(toClass.isPrimitive());
}
//autoboxing:
if (autoboxing) {
if (cls.isPrimitive() && !toClass.isPrimitive()) {
cls = primitiveToWrapper(cls);
if (cls == null) {
return false;
}
}
if (toClass.isPrimitive() && !cls.isPrimitive()) {
cls = wrapperToPrimitive(cls);
if (cls == null) {
return false;
}
}
}
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.
* *NOTE: From v2.2, this method handles Void.TYPE,
* returning Void.TYPE.
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;
}
/**
* Converts the specified wrapper class to its corresponding primitive * class.
* *This method is the counter part of primitiveToWrapper().
* If the passed in class is a wrapper class for a primitive type, this
* primitive type will be returned (e.g. Integer.TYPE for
* Integer.class). For other classes, or if the parameter is
* null, the return value is null.
cls is a
* wrapper class, null otherwise
* @see #primitiveToWrapper(Class)
* @since 2.4
*/
public static Class wrapperToPrimitive(Class cls) {
return (Class) wrapperPrimitiveMap.get(cls);
}
/**
* Converts the specified array of wrapper Class objects to an array of * its corresponding primitive Class objects.
* *This method invokes wrapperToPrimitive() for each element
* of the passed in array.
null if null input.
* Empty array if an empty array passed in.
* @see #wrapperToPrimitive(Class)
* @since 2.4
*/
public static Class[] wrappersToPrimitives(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] = wrapperToPrimitive(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 * @returntrue 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;
}
// Class loading
// ----------------------------------------------------------------------
/**
* Returns the class represented by className using the
* classLoader. This implementation supports the syntaxes
* "java.util.Map.Entry[]", "java.util.Map$Entry[]",
* "[Ljava.util.Map.Entry;", and "[Ljava.util.Map$Entry;".
*
* @param classLoader the class loader to use to load the class
* @param className the class name
* @param initialize whether the class must be initialized
* @return the class represented by className using the classLoader
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(
ClassLoader classLoader, String className, boolean initialize) throws ClassNotFoundException {
try {
Class clazz;
if (abbreviationMap.containsKey(className)) {
String clsName = "[" + abbreviationMap.get(className);
clazz = Class.forName(clsName, initialize, classLoader).getComponentType();
} else {
clazz = Class.forName(toCanonicalName(className), initialize, classLoader);
}
return clazz;
} catch (ClassNotFoundException ex) {
// allow path separators (.) as inner class name separators
int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (lastDotIndex != -1) {
try {
return getClass(classLoader, className.substring(0, lastDotIndex) +
INNER_CLASS_SEPARATOR_CHAR + className.substring(lastDotIndex + 1),
initialize);
} catch (ClassNotFoundException ex2) {
}
}
throw ex;
}
}
/**
* Returns the (initialized) class represented by className
* using the classLoader. This implementation supports
* the syntaxes "java.util.Map.Entry[]",
* "java.util.Map$Entry[]", "[Ljava.util.Map.Entry;",
* and "[Ljava.util.Map$Entry;".
*
* @param classLoader the class loader to use to load the class
* @param className the class name
* @return the class represented by className using the classLoader
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(ClassLoader classLoader, String className) throws ClassNotFoundException {
return getClass(classLoader, className, true);
}
/**
* Returns the (initialized) class represented by className
* using the current thread's context class loader. This implementation
* supports the syntaxes "java.util.Map.Entry[]",
* "java.util.Map$Entry[]", "[Ljava.util.Map.Entry;",
* and "[Ljava.util.Map$Entry;".
*
* @param className the class name
* @return the class represented by className using the current thread's context class loader
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(String className) throws ClassNotFoundException {
return getClass(className, true);
}
/**
* Returns the class represented by className using the
* current thread's context class loader. This implementation supports the
* syntaxes "java.util.Map.Entry[]", "java.util.Map$Entry[]",
* "[Ljava.util.Map.Entry;", and "[Ljava.util.Map$Entry;".
*
* @param className the class name
* @param initialize whether the class must be initialized
* @return the class represented by className using the current thread's context class loader
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(String className, boolean initialize) throws ClassNotFoundException {
ClassLoader contextCL = Thread.currentThread().getContextClassLoader();
ClassLoader loader = contextCL == null ? ClassUtils.class.getClassLoader() : contextCL;
return getClass(loader, className, initialize );
}
// Public method
// ----------------------------------------------------------------------
/**
* Returns the desired Method much like Class.getMethod, however
* it ensures that the returned Method is from a public class or interface and not
* from an anonymous inner class. This means that the Method is invokable and
* doesn't fall foul of Java bug
* 4071957).
*
* Set set = Collections.unmodifiableSet(...);
* Method method = ClassUtils.getPublicMethod(set.getClass(), "isEmpty", new Class[0]);
* Object result = method.invoke(set, new Object[]);
Converts an array of Object in to an array of Class objects.
* If any of these objects is null, a null element will be inserted into the array.
This method returns null for a null input array.
Object array
* @return a Class array, null if null array input
* @since 2.4
*/
public static Class[] toClass(Object[] array) {
if (array == null) {
return null;
} else if (array.length == 0) {
return ArrayUtils.EMPTY_CLASS_ARRAY;
}
Class[] classes = new Class[array.length];
for (int i = 0; i < array.length; i++) {
classes[i] = array[i] == null ? null : array[i].getClass();
}
return classes;
}
// Short canonical name
// ----------------------------------------------------------------------
/**
* Gets the canonical name minus the package name for an Object.
Gets the canonical name minus the package name from a Class.
Gets the canonical name minus the package name from a String.
* *The string passed in is assumed to be a canonical name - it is not checked.
* * @param canonicalName the class name to get the short name for * @return the canonical name of the class without the package name or an empty string * @since 2.4 */ public static String getShortCanonicalName(String canonicalName) { return ClassUtils.getShortClassName(getCanonicalName(canonicalName)); } // Package name // ---------------------------------------------------------------------- /** *Gets the package name from the canonical name of an Object.
Gets the package name from the canonical name of a Class.
null.
* @return the package name or an empty string
* @since 2.4
*/
public static String getPackageCanonicalName(Class cls) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getPackageCanonicalName(cls.getName());
}
/**
* Gets the package name from the canonical name.
* *The string passed in is assumed to be a canonical name - it is not checked.
*If the class is unpackaged, return an empty string.
* * @param canonicalName the canonical name to get the package name for, may benull
* @return the package name or an empty string
* @since 2.4
*/
public static String getPackageCanonicalName(String canonicalName) {
return ClassUtils.getPackageName(getCanonicalName(canonicalName));
}
/**
* Converts a given name of class into canonical format. * If name of class is not a name of array class it returns * unchanged name.
*Example: *
getCanonicalName("[I") = "int[]"getCanonicalName("[Ljava.lang.String;") = "java.lang.String[]"getCanonicalName("java.lang.String") = "java.lang.String"