org.apache.commons.lang

Class ClassUtils

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 161243 2005-04-14 04:30:28Z ggregory $

Author: Stephen Colebourne Gary Gregory Norm Deane

Field Summary
static StringINNER_CLASS_SEPARATOR

The inner class separator String: "$".

static charINNER_CLASS_SEPARATOR_CHAR

The inner class separator character: '$' == {@value}.

static StringPACKAGE_SEPARATOR

The package separator String: ".".

static charPACKAGE_SEPARATOR_CHAR

The package separator character: '.' == {@value}.

Constructor Summary
ClassUtils()

ClassUtils instances should NOT be constructed in standard programming.

Method Summary
static ListconvertClassesToClassNames(List classes)

Given a List of Class objects, this method converts them into class names.

A new List is returned.

static ListconvertClassNamesToClasses(List classNames)

Given a List of class names, this method converts them into classes.

A new List is returned.

static ListgetAllInterfaces(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.

static ListgetAllSuperclasses(Class cls)

Gets a List of superclasses for the given class.

static StringgetPackageName(Object object, String valueIfNull)

Gets the package name of an Object.

static StringgetPackageName(Class cls)

Gets the package name of a Class.

static StringgetPackageName(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.

static StringgetShortClassName(Object object, String valueIfNull)

Gets the class name minus the package name for an Object.

static StringgetShortClassName(Class cls)

Gets the class name minus the package name from a Class.

static StringgetShortClassName(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 booleanisAssignable(Class[] classArray, Class[] toClassArray)

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.

static booleanisAssignable(Class cls, Class toClass)

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.

static booleanisInnerClass(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 ClassprimitiveToWrapper(Class cls)

Converts the specified primitive Class object to its corresponding wrapper Class object.

Field Detail

INNER_CLASS_SEPARATOR

public static final String INNER_CLASS_SEPARATOR

The inner class separator String: "$".

INNER_CLASS_SEPARATOR_CHAR

public static final char INNER_CLASS_SEPARATOR_CHAR

The inner class separator character: '$' == {@value}.

PACKAGE_SEPARATOR

public static final String PACKAGE_SEPARATOR

The package separator String: ".".

PACKAGE_SEPARATOR_CHAR

public static final char PACKAGE_SEPARATOR_CHAR

The package separator character: '.' == {@value}.

Constructor Detail

ClassUtils

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.

Method Detail

convertClassesToClassNames

public static List convertClassesToClassNames(List 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.

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

convertClassNamesToClasses

public static List convertClassNamesToClasses(List 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.

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

getAllInterfaces

public static List 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.

Parameters: cls the class to look up, may be null

Returns: the List of interfaces in order, null if null input

getAllSuperclasses

public static List getAllSuperclasses(Class cls)

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

getPackageName

public static String getPackageName(Object object, String valueIfNull)

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

getPackageName

public static String getPackageName(Class cls)

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

getPackageName

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.

Parameters: className the className to get the package name for, may be null

Returns: the package name or an empty string

getShortClassName

public static String getShortClassName(Object object, String valueIfNull)

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

getShortClassName

public static String getShortClassName(Class cls)

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

getShortClassName

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.

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

isAssignable

public static boolean isAssignable(Class[] classArray, Class[] toClassArray)

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.

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

isAssignable

public static boolean isAssignable(Class cls, Class toClass)

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.

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

isInnerClass

public static boolean isInnerClass(Class cls)

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

primitivesToWrappers

public static Class[] primitivesToWrappers(Class[] classes)

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

primitiveToWrapper

public static Class primitiveToWrapper(Class cls)

Converts the specified primitive Class object to its corresponding wrapper Class object.

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

Copyright © 2001-2005 - Apache Software Foundation