org.apache.commons.lang
public class ClassUtils extends Object
Operates on classes without using reflection.
This class handles invalid null
inputs as best it can.
Each method documents its behaviour in more detail.
Since: 2.0
Version: $Id: ClassUtils.java 633621 2008-03-04 20:20:23Z mbenson $
Field Summary | |
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static String | INNER_CLASS_SEPARATOR The inner class separator String: |
static char | INNER_CLASS_SEPARATOR_CHAR The inner class separator character: |
static String | PACKAGE_SEPARATOR The package separator String: |
static char | PACKAGE_SEPARATOR_CHAR The package separator character: |
Constructor Summary | |
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ClassUtils() ClassUtils instances should NOT be constructed in standard programming. |
Method Summary | |
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static List | convertClassesToClassNames(List classes) Given a A new |
static List | convertClassNamesToClasses(List classNames) Given a A new |
static List | getAllInterfaces(Class cls) Gets a The order is determined by looking through each interface in turn as declared in the source file and following its hierarchy up. |
static List | getAllSuperclasses(Class cls) Gets a |
static Class | getClass(ClassLoader classLoader, String className, boolean initialize)
Returns the class represented by className using the
classLoader . |
static Class | getClass(ClassLoader classLoader, String className)
Returns the (initialized) class represented by className
using the classLoader . |
static Class | getClass(String className)
Returns the (initialized )class represented by className
using the current thread's context class loader. |
static Class | getClass(String className, boolean initialize)
Returns the class represented by className using the
current thread's context class loader. |
static String | getPackageCanonicalName(Object object, String valueIfNull) Gets the package name from the canonical name of an |
static String | getPackageCanonicalName(Class cls) Gets the package name from the canonical name of a |
static String | getPackageCanonicalName(String canonicalName) Gets the package name from the canonical name. |
static String | getPackageName(Object object, String valueIfNull) Gets the package name of an |
static String | getPackageName(Class cls) Gets the package name of a |
static String | getPackageName(String className) Gets the package name from a The string passed in is assumed to be a class name - it is not checked. If the class is unpackaged, return an empty string. |
static Method | getPublicMethod(Class cls, String methodName, Class[] parameterTypes) Returns the desired Method much like |
static String | getShortCanonicalName(Object object, String valueIfNull) Gets the canonical name minus the package name for an |
static String | getShortCanonicalName(Class cls) Gets the canonical name minus the package name from a |
static String | getShortCanonicalName(String canonicalName) 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. |
static String | getShortClassName(Object object, String valueIfNull) Gets the class name minus the package name for an |
static String | getShortClassName(Class cls) Gets the class name minus the package name from a |
static String | getShortClassName(String className) 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. |
static boolean | isAssignable(Class[] classArray, Class[] toClassArray) Checks if an array of Classes can be assigned to another array of Classes. This method calls |
static boolean | isAssignable(Class cls, Class toClass) Checks if one Unlike the Class#isAssignableFrom(java.lang.Class) method,
this method takes into account widenings of primitive classes and
Primitive widenings allow an int to be assigned to a long, float or double. |
static boolean | isInnerClass(Class cls) Is the specified class an inner class or static nested class. |
static Class[] | primitivesToWrappers(Class[] classes) Converts the specified array of primitive Class objects to an array of its corresponding wrapper Class objects. |
static Class | primitiveToWrapper(Class cls) Converts the specified primitive Class object to its corresponding wrapper Class object. NOTE: From v2.2, this method handles |
static Class[] | toClass(Object[] array) Converts an array of This method returns |
static Class[] | wrappersToPrimitives(Class[] classes) Converts the specified array of wrapper Class objects to an array of its corresponding primitive Class objects. This method invokes |
static Class | wrapperToPrimitive(Class cls) Converts the specified wrapper class to its corresponding primitive class. This method is the counter part of |
The inner class separator String: "$"
.
The inner class separator character: '$' == {@value }
.
The package separator String: "."
.
The package separator character: '.' == {@value }
.
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.
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
.
Parameters: classes the classes to change
Returns: a List
of class names corresponding to the Class objects,
null
if null input
Throws: ClassCastException if classes
contains a non-Class
entry
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
.
Parameters: classNames the classNames to change
Returns: a List
of Class objects corresponding to the class names,
null
if null input
Throws: ClassCastException if classNames contains a non String entry
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.
Parameters: cls the class to look up, may be null
Returns: the List
of interfaces in order,
null
if null input
Gets a List
of superclasses for the given class.
Parameters: cls the class to look up, may be null
Returns: the List
of superclasses in order going up from this one
null
if null input
className
using the
classLoader
. This implementation supports names like
"java.lang.String[]
" as well as "[Ljava.lang.String;
".
Parameters: classLoader the class loader to use to load the class className the class name initialize whether the class must be initialized
Returns: the class represented by className
using the classLoader
Throws: ClassNotFoundException if the class is not found
className
using the classLoader
. This implementation supports names
like "java.lang.String[]
" as well as
"[Ljava.lang.String;
".
Parameters: classLoader the class loader to use to load the class className the class name
Returns: the class represented by className
using the classLoader
Throws: ClassNotFoundException if the class is not found
className
using the current thread's context class loader. This implementation
supports names like "java.lang.String[]
" as well as
"[Ljava.lang.String;
".
Parameters: className the class name
Returns: the class represented by className
using the current thread's context class loader
Throws: ClassNotFoundException if the class is not found
className
using the
current thread's context class loader. This implementation supports
names like "java.lang.String[]
" as well as
"[Ljava.lang.String;
".
Parameters: className the class name initialize whether the class must be initialized
Returns: the class represented by className
using the current thread's context class loader
Throws: ClassNotFoundException if the class is not found
Gets the package name from the canonical name of an Object
.
Parameters: object the class to get the package name for, may be null valueIfNull the value to return if null
Returns: the package name of the object, or the null value
Since: 2.4
Gets the package name from the canonical name of a Class
.
Parameters: cls the class to get the package name for, may be null
.
Returns: the package name or an empty string
Since: 2.4
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.
Parameters: canonicalName the canonical name to get the package name for, may be null
Returns: the package name or an empty string
Since: 2.4
Gets the package name of an Object
.
Parameters: object the class to get the package name for, may be null valueIfNull the value to return if null
Returns: the package name of the object, or the null value
Gets the package name of a Class
.
Parameters: cls the class to get the package name for, may be null
.
Returns: the package name or an empty string
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.
Parameters: className the className to get the package name for, may be null
Returns: the package name or an empty string
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[]);
Parameters: cls the class to check, not null methodName the name of the method parameterTypes the list of parameters
Returns: the method
Throws: NullPointerException if the class is null SecurityException if a a security violation occured NoSuchMethodException if the method is not found in the given class or if the metothod doen't conform with the requirements
Gets the canonical name minus the package name for an Object
.
Parameters: object the class to get the short name for, may be null valueIfNull the value to return if null
Returns: the canonical name of the object without the package name, or the null value
Since: 2.4
Gets the canonical name minus the package name from a Class
.
Parameters: cls the class to get the short name for.
Returns: the canonical name without the package name or an empty string
Since: 2.4
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.
Parameters: canonicalName the class name to get the short name for
Returns: the canonical name of the class without the package name or an empty string
Since: 2.4
Gets the class name minus the package name for an Object
.
Parameters: object the class to get the short name for, may be null valueIfNull the value to return if null
Returns: the class name of the object without the package name, or the null value
Gets the class name minus the package name from a Class
.
Parameters: cls the class to get the short name for.
Returns: the class name without the package name or an empty string
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.
Parameters: className the className to get the short name for
Returns: the class name of the class without the package name or an empty string
Checks if an array of Classes can be assigned to another array of Classes.
This method calls 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 Class#isAssignableFrom(java.lang.Class) method, this
method takes into account widenings of primitive classes and
null
s.
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.
Parameters: classArray the array of Classes to check, may be null
toClassArray the array of Classes to try to assign into, may be null
Returns: true
if assignment possible
Checks if one Class
can be assigned to a variable of
another Class
.
Unlike the Class#isAssignableFrom(java.lang.Class) method,
this method takes into account widenings of primitive classes and
null
s.
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.
Parameters: cls the Class to check, may be null toClass the Class to try to assign into, returns false if null
Returns: true
if assignment possible
Is the specified class an inner class or static nested class.
Parameters: cls the class to check, may be null
Returns: true
if the class is an inner or static nested class,
false if not or null
Converts the specified array of primitive Class objects to an array of its corresponding wrapper Class objects.
Parameters: classes the class array to convert, may be null or empty
Returns: 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
Converts the specified primitive Class object to its corresponding wrapper Class object.
NOTE: From v2.2, this method handles Void.TYPE
,
returning Void.TYPE
.
Parameters: cls the class to convert, may be null
Returns: the wrapper class for cls
or cls
if
cls
is not a primitive. null
if null input.
Since: 2.1
Converts an array of Object
in to an array of Class
objects.
This method returns null
for a null
input array.
Parameters: array an Object
array
Returns: a Class
array, null
if null array input
Since: 2.4
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.
Parameters: classes the class array to convert, may be null or empty
Returns: an array which contains for each given class, the primitive class or
null if the original class is not a wrapper class. null
if null input.
Empty array if an empty array passed in.
Since: 2.4
See Also: wrapperToPrimitive
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.
Parameters: cls the class to convert, may be null
Returns: the corresponding primitive type if cls
is a
wrapper class, null otherwise
Since: 2.4
See Also: primitiveToWrapper