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.
Modifier and Type | Field and Description |
---|---|
static Comparator<Class<?>> |
CLASS_NAME_COMPARATOR
Compares two
Class s by name. |
static String |
INNER_CLASS_SEPARATOR
The inner class separator String:
"$" . |
static char |
INNER_CLASS_SEPARATOR_CHAR
The inner class separator character:
'$' == $ . |
static Comparator<Package> |
PACKAGE_NAME_COMPARATOR
Compares two
Package s by name. |
static String |
PACKAGE_SEPARATOR
The package separator String:
"." . |
static char |
PACKAGE_SEPARATOR_CHAR
The package separator character:
'.' == . . |
Constructor and Description |
---|
ClassUtils()
ClassUtils instances should NOT be constructed in standard programming.
|
Modifier and Type | Method and Description |
---|---|
static List<String> |
convertClassesToClassNames(List<Class<?>> classes)
Given a
List of Class objects, this method
converts them into class names. |
static List<Class<?>> |
convertClassNamesToClasses(List<String> classNames)
Given a
List of class names, this method converts them
into classes. |
static List<Class<?>> |
getAllInterfaces(Class<?> cls)
Gets a
List of all interfaces implemented by the given
class and its superclasses. |
static List<Class<?>> |
getAllSuperclasses(Class<?> cls)
Gets a
List of superclasses for the given class. |
static String |
getPackageName(Class<?> cls)
Gets the package name of a
Class . |
static String |
getPackageName(Object object,
String valueIfNull)
Gets the package name of an
Object . |
static String |
getPackageName(String className)
Gets the package name from a
String . |
static String |
getShortClassName(Class<?> cls)
Gets the class name minus the package name from a
Class . |
static String |
getShortClassName(Object object,
String valueIfNull)
Gets the class name minus the package name for an
Object . |
static String |
getShortClassName(String className)
Gets the class name minus the package name from a String.
|
static boolean |
isAssignable(Class<?>[] classArray,
Class<?>[] toClassArray)
Checks if an array of Classes can be assigned to another array of
Classes.
|
static boolean |
isAssignable(Class<?> cls,
Class<?> toClass)
Checks if one
Class can be assigned to a variable of
another Class . |
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.
|
public static final char PACKAGE_SEPARATOR_CHAR
The package separator character: '.' == .
.
public static final String PACKAGE_SEPARATOR
The package separator String: "."
.
public static final char INNER_CLASS_SEPARATOR_CHAR
The inner class separator character: '$' == $
.
public static final String INNER_CLASS_SEPARATOR
The inner class separator String: "$"
.
public static final Comparator<Class<?>> CLASS_NAME_COMPARATOR
Class
s by name.public static final Comparator<Package> PACKAGE_NAME_COMPARATOR
Package
s by name.public ClassUtils()
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 static String getShortClassName(Object object, String valueIfNull)
Gets the class name minus the package name for an Object
.
object
- the class to get the short name for, may be nullvalueIfNull
- the value to return if nullpublic static String getShortClassName(Class<?> cls)
Gets the class name minus the package name from a Class
.
cls
- the class to get the short name for.public 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.
className
- the className to get the short name forpublic static String getPackageName(Object object, String valueIfNull)
Gets the package name of an Object
.
object
- the class to get the package name for, may be nullvalueIfNull
- the value to return if nullpublic static String getPackageName(Class<?> cls)
Gets the package name of a Class
.
cls
- the class to get the package name for, may be
null
.public static String getPackageName(String className)
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.
className
- the className to get the package name for, may be
null
public static List<Class<?>> getAllSuperclasses(Class<?> cls)
Gets a List
of superclasses for the given class.
cls
- the class to look up, may be null
List
of superclasses in order going up from
this one null
if null inputpublic static List<Class<?>> getAllInterfaces(Class<?> cls)
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.
cls
- the class to look up, may be null
List
of interfaces in order, null
if null inputpublic static List<Class<?>> convertClassNamesToClasses(List<String> classNames)
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
.
classNames
- the classNames to changeList
of Class objects corresponding to the class
names, null
if null inputClassCastException
- if classNames contains a non String entrypublic static List<String> convertClassesToClassNames(List<Class<?>> 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
.
classes
- the classes to changeList
of class names corresponding to the Class
objects, null
if null inputClassCastException
- if classes
contains a non-Class
entrypublic static boolean isAssignable(Class<?>[] classArray, Class<?>[] toClassArray)
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.
classArray
- the array of Classes to check, may be null
toClassArray
- the array of Classes to try to assign into, may be
null
true
if assignment possiblepublic static boolean isAssignable(Class<?> cls, Class<?> toClass)
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.
cls
- the Class to check, may be nulltoClass
- the Class to try to assign into, returns false if nulltrue
if assignment possiblepublic static Class<?> primitiveToWrapper(Class<?> cls)
Converts the specified primitive Class object to its corresponding wrapper Class object.
cls
- the class to convert, may be nullcls
or cls
if
cls
is not a primitive. null
if
null input.public static Class<?>[] primitivesToWrappers(Class<?>[] classes)
Converts the specified array of primitive Class objects to an array of its corresponding wrapper Class objects.
classes
- the class array to convert, may be null or emptynull
if null input. Empty array if an empty array
passed in.public static boolean isInnerClass(Class<?> cls)
Is the specified class an inner class or static nested class.
cls
- the class to check, may be nulltrue
if the class is an inner or static nested
class, false if not or null
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