org.datanucleus.util
Class ClassUtils

java.lang.Object
  org.datanucleus.util.ClassUtils

public class ClassUtils
extends java.lang.Object

Utilities for handling classes. These are to supplement the methods provided by the Class object.

Field Summary

protected static java.util.Map	constructorsCache caching for constructors - using caching, the perf is at least doubled
protected static Localiser	LOCALISER Localisation utility for output messages

Constructor Summary

ClassUtils()

Method Summary

static void	assertClassForJarExistsInClasspath(ClassLoaderResolver clr, java.lang.String className, java.lang.String jarName) Convenience method to throw a NucleusUserException if the specified class is not loadable from the ClassLoaderResolver.
static boolean	classesAreDescendents(ClassLoaderResolver clr, java.lang.String class_name_1, java.lang.String class_name_2) Method to check if 2 classes are direct descendents.
static java.lang.Object	convertValue(java.lang.Object value, java.lang.Class cls) Convenience method to convert the passed value to an object of the specified type (if possible).
static java.lang.String	createFullClassName(java.lang.String pkg_name, java.lang.String cls_name) Utility to create the full class name given the package and class name.
static void	dumpClassInformation(java.lang.Class cls) Utility to use Reflection to dump out the details of a class.
static java.util.Collection	getClassFilesForDirectory(java.io.File dir, boolean normal_classes, boolean inner_classes) Method to return the class files below the specified directory.
static java.lang.Class	getClassForMemberOfClass(java.lang.Class cls, java.lang.String memberName) Method that returns the class type of a member of the specified class (if present).
static java.lang.String	getClassNameForClass(java.lang.Class cls) Utility to return the class name without the package name for a class.
static java.lang.String	getClassnameForFilename(java.lang.String filename, java.lang.String rootfilename) Utility to get the Class name given the file name and the file name of the root of the package structure.
static java.lang.String	getClassNameForFileURL(java.net.URL fileURL) Utility to find the class name of a class given the absolute file name of its class file.
static java.lang.String[]	getClassNamesForDirectoryAndBelow(java.io.File dir) Convenience method to return the names of classes specified in the directory and below.
static java.lang.String[]	getClassNamesForJarFile(java.lang.String jarFileName) Convenience accessor for the names of all class files in the jar file with the specified name.
static java.lang.String[]	getClassNamesForJarFile(java.net.URL jarFileURL) Convenience accessor for the names of all class files in the jar file with the specified URL.
static java.lang.String	getCollectionElementType(java.lang.Class type, java.lang.reflect.Type genericType) Convenience method to extract the element type of a collection when using JDK1.5 generics given the input field.
static java.lang.String	getCollectionElementType(java.lang.reflect.Field field) Convenience method to extract the element type of a collection when using JDK1.5 generics given the input field.
static java.lang.String	getCollectionElementType(java.lang.reflect.Method method) Convenience method to extract the element type of a collection when using JDK1.5 generics, given the input method (getter).
static java.lang.reflect.Constructor	getConstructorWithArguments(java.lang.Class cls, java.lang.Class[] types) Convenience method to return the constructor of the passed class that accepts the supplied argument types.
static java.lang.reflect.Field	getFieldForClass(java.lang.Class cls, java.lang.String fieldName) Obtain a field from a class or superclasses using reflection.
static java.lang.String	getFieldNameForJavaBeanGetter(java.lang.String methodName) Generate a field name for JavaBeans compatible getter method
static java.lang.String	getFieldNameForJavaBeanSetter(java.lang.String methodName) Generate a field name for JavaBeans compatible setter method
static java.lang.reflect.Method	getGetterMethodForClass(java.lang.Class cls, java.lang.String beanName) Obtain a (Java bean) getter method from a class or superclasses using reflection.
static java.lang.String	getJavaBeanGetterName(java.lang.String fieldName, boolean isBoolean) Generate a JavaBeans compatible getter name
static java.lang.String	getJavaBeanSetterName(java.lang.String fieldName) Generate a JavaBeans compatible setter name
static java.lang.String	getJavaLangClassForType(java.lang.String type) Convenience method to return the passed type as a java.lang type wherever possible.
static java.lang.String	getMapKeyType(java.lang.Class type, java.lang.reflect.Type genericType) Convenience method to extract the key type of a map when using JDK1.5 generics given the input field.
static java.lang.String	getMapKeyType(java.lang.reflect.Field field) Convenience method to extract the key type of a map when using JDK1.5 generics given the input field.
static java.lang.String	getMapKeyType(java.lang.reflect.Method method) Convenience method to extract the key type of a map when using JDK1.5 generics given the input method.
static java.lang.String	getMapValueType(java.lang.Class type, java.lang.reflect.Type genericType) Convenience method to extract the value type of a map when using JDK1.5 generics given the input field
static java.lang.String	getMapValueType(java.lang.reflect.Field field) Convenience method to extract the value type of a map when using JDK1.5 generics given the input field
static java.lang.String	getMapValueType(java.lang.reflect.Method method) Convenience method to extract the value type of a map when using JDK1.5 generics given the input method.
static java.lang.reflect.Method	getMethodForClass(java.lang.Class cls, java.lang.String methodName, java.lang.Class[] argtypes) Obtain a method from a class or superclasses using reflection
static java.lang.reflect.Method	getMethodWithArgument(java.lang.Class cls, java.lang.String methodName, java.lang.Class argType) Obtain a method from a class or superclasses using reflection.
static int	getModifiersForFieldOfClass(ClassLoaderResolver clr, java.lang.String className, java.lang.String fieldName) Convenience accessor for the modifiers of a field in a class.
static java.lang.String[]	getPackageJdoFilesForJarFile(java.lang.String jarFileName) Convenience accessor for the names of all "package.jdo" files in the jar file with the specified name.
static java.lang.String[]	getPackageJdoFilesForJarFile(java.net.URL jarFileURL) Convenience accessor for the names of all "package.jdo" files in the jar file with the specified URL.
static java.lang.String	getPackageNameForClass(java.lang.Class cls) Utility to return the package name for a class.
static java.lang.Class	getPrimitiveTypeForType(java.lang.Class type) Method to return the primitive equivalent of the specified type (if any).
static java.util.Collection	getSuperclasses(java.lang.Class the_class) Method to return the superclasses for a class.
static java.util.Collection	getSuperinterfaces(java.lang.Class the_class) Method to return the superinterfaces for a class.
static java.lang.Object	getValueForIdentityField(java.lang.Object id, java.lang.String fieldName) Method to find the value of a field of the provided user-defined identity.
static java.lang.Object	getValueOfFieldByReflection(java.lang.Object object, java.lang.String fieldName) Helper method to return the value of a field of an object using reflection.
static java.lang.Object	getValueOfMethodByReflection(java.lang.Object object, java.lang.String methodName, java.lang.Object... args) Helper method to return the value returned by a method on an object using reflection.
static java.lang.Class	getWrapperTypeForPrimitiveType(java.lang.Class type) Convenience method to return the object wrapper type for a primitive type.
static java.lang.String	getWrapperTypeNameForPrimitiveTypeName(java.lang.String typeName) Convenience method to return the object wrapper type for a primitive type name.
static boolean	hasDefaultConstructor(java.lang.Class the_class) Method to check for a default constructor on a class.
static boolean	isInnerClass(java.lang.String class_name) Method to check whether a classname is for an inner class.
static boolean	isPrimitiveArrayType(java.lang.String typeName) Convenience method to return if the passed type (name) is a primitive array type.
static boolean	isPrimitiveType(java.lang.String typeName) Convenience method to return if the passed type (name) is a primitive type.
static boolean	isPrimitiveWrapperType(java.lang.String typeName) Convenience method to return if the passed type (name) is a primitive wrapper type.
static boolean	isReferenceType(java.lang.Class cls) Method to return whether the passes type is a "reference" type.
static java.lang.Object	newInstance(java.lang.Class type, java.lang.Class[] parameterTypes, java.lang.Object[] parameters) Accessor for a new instance of an object.
static boolean	stringArrayContainsValue(java.lang.String[] array, java.lang.String value) Convenience method to return if a String array contains a value.
static boolean	typesAreCompatible(java.lang.Class cls1, java.lang.Class cls2) Convenience method to return if two types are compatible.
static boolean	typesAreCompatible(java.lang.Class cls1, java.lang.String clsName2, ClassLoaderResolver clr) Convenience method to return if two types are compatible.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOCALISER

protected static final Localiser LOCALISER

Localisation utility for output messages

constructorsCache

protected static java.util.Map constructorsCache

caching for constructors - using caching, the perf is at least doubled

Constructor Detail

ClassUtils

public ClassUtils()

Method Detail

newInstance

public static java.lang.Object newInstance(java.lang.Class type,
                                           java.lang.Class[] parameterTypes,
                                           java.lang.Object[] parameters)

Accessor for a new instance of an object. Uses reflection to generate the instance using the passed constructor parameter arguments.

Parameters:

type - Type of object (the class).

parameterTypes - Classes of params for the constructor

parameters - The parameters for the constructor

Returns:

The object

Throws:

NucleusException - If an error occurs creating the instance

getConstructorWithArguments

public static java.lang.reflect.Constructor getConstructorWithArguments(java.lang.Class cls,
                                                                        java.lang.Class[] types)

Convenience method to return the constructor of the passed class that accepts the supplied argument types. Allows for primitive to primitive wrapper conversion. Typically used by the JDOQL ResultClass mapping process.

Parameters:

cls - The class

types - The constructor argument types

Returns:

The constructor

getMethodWithArgument

public static java.lang.reflect.Method getMethodWithArgument(java.lang.Class cls,
                                                             java.lang.String methodName,
                                                             java.lang.Class argType)

Obtain a method from a class or superclasses using reflection. The method will have the specified name and will take a single argument. Allows for the argument type being primitive or its associated wrapper.

Parameters:

cls - the class to find the declared fields and populate the map

methodName - the method name to find

argType - the argument type

getMethodForClass

public static java.lang.reflect.Method getMethodForClass(java.lang.Class cls,
                                                         java.lang.String methodName,
                                                         java.lang.Class[] argtypes)

Obtain a method from a class or superclasses using reflection

Parameters:

cls - the class where to look for the method

methodName - the method name to find

argtypes - the classes argument of the method

Returns:

The Method

getClassnameForFilename

public static java.lang.String getClassnameForFilename(java.lang.String filename,
                                                       java.lang.String rootfilename)

Utility to get the Class name given the file name and the file name of the root of the package structure.

Parameters:

filename - The filename of the class file

rootfilename - The filename of the root of the package structure

Returns:

The Class name

getClassFilesForDirectory

public static java.util.Collection getClassFilesForDirectory(java.io.File dir,
                                                             boolean normal_classes,
                                                             boolean inner_classes)

Method to return the class files below the specified directory.

Parameters:

dir - The directory

normal_classes - Whether to include normal classes

inner_classes - Whether to include inner classes

Returns:

The class files (Collection of File objects).

getClassNamesForJarFile

public static java.lang.String[] getClassNamesForJarFile(java.lang.String jarFileName)

Convenience accessor for the names of all class files in the jar file with the specified name. The returned class names are of the form "org.datanucleus.MyClass".

Parameters:

jarFileName - Name of the jar file

Returns:

The class names

getClassNamesForJarFile

public static java.lang.String[] getClassNamesForJarFile(java.net.URL jarFileURL)

Convenience accessor for the names of all class files in the jar file with the specified URL. The returned class names are of the form "org.datanucleus.MyClass".

Parameters:

jarFileURL - URL for the jar file

Returns:

The class names

getPackageJdoFilesForJarFile

public static java.lang.String[] getPackageJdoFilesForJarFile(java.lang.String jarFileName)

Convenience accessor for the names of all "package.jdo" files in the jar file with the specified name.

Parameters:

jarFileName - Name of the jar file

Returns:

The "package.jdo" file names

getPackageJdoFilesForJarFile

public static java.lang.String[] getPackageJdoFilesForJarFile(java.net.URL jarFileURL)

Convenience accessor for the names of all "package.jdo" files in the jar file with the specified URL.

Parameters:

jarFileURL - URL for the jar file

Returns:

The "package.jdo" file names

getClassNamesForDirectoryAndBelow

public static java.lang.String[] getClassNamesForDirectoryAndBelow(java.io.File dir)

Convenience method to return the names of classes specified in the directory and below. All inner classes are ignored.

Parameters:

dir - Directory that we should look below (root of classpath)

Returns:

The class names

isInnerClass

public static boolean isInnerClass(java.lang.String class_name)

Method to check whether a classname is for an inner class. Currently checks for the presence of $ in the name.

Parameters:

class_name - The class name

Returns:

Whether it is an inner class

hasDefaultConstructor

public static boolean hasDefaultConstructor(java.lang.Class the_class)

Method to check for a default constructor on a class. Particular relevance for JDO is the requirement for a default constructor on all Persistence-Capable classes. Doesn't check superclasses for the default constructor.

Parameters:

the_class - The class

Returns:

Whether it has a default constructor

getSuperclasses

public static java.util.Collection getSuperclasses(java.lang.Class the_class)

Method to return the superclasses for a class. The superclasses will be ordered.

Parameters:

the_class - The class

Returns:

The superclass of this class.

getSuperinterfaces

public static java.util.Collection getSuperinterfaces(java.lang.Class the_class)

Method to return the superinterfaces for a class. The superinterfaces will be ordered.

Parameters:

the_class - The class

Returns:

The superinterfaces of this class.

getFieldForClass

public static java.lang.reflect.Field getFieldForClass(java.lang.Class cls,
                                                       java.lang.String fieldName)

Obtain a field from a class or superclasses using reflection.

Parameters:

cls - the class to find the field from

fieldName - the field name to find

Returns:

The Field

getGetterMethodForClass

public static java.lang.reflect.Method getGetterMethodForClass(java.lang.Class cls,
                                                               java.lang.String beanName)

Obtain a (Java bean) getter method from a class or superclasses using reflection.

Parameters:

cls - the class to find the getter from

beanName - the name of the java bean to find the getter for

Returns:

The getter Method

getWrapperTypeNameForPrimitiveTypeName

public static java.lang.String getWrapperTypeNameForPrimitiveTypeName(java.lang.String typeName)

Convenience method to return the object wrapper type for a primitive type name. If the type is not a primitive then just returns the type name

Parameters:

typeName - The primitive type name

Returns:

The object wrapper type name for this primitive

getWrapperTypeForPrimitiveType

public static java.lang.Class getWrapperTypeForPrimitiveType(java.lang.Class type)

Convenience method to return the object wrapper type for a primitive type.

Parameters:

type - The primitive type

Returns:

The object wrapper type for this primitive

getPrimitiveTypeForType

public static java.lang.Class getPrimitiveTypeForType(java.lang.Class type)

Method to return the primitive equivalent of the specified type (if any). Returns null if there is no primitive equivalent.

Parameters:

type - The type

Returns:

The primitive equivalent.

isPrimitiveWrapperType

public static boolean isPrimitiveWrapperType(java.lang.String typeName)

Convenience method to return if the passed type (name) is a primitive wrapper type.

Parameters:

typeName - Name of the type

Returns:

Whether it is a primitive wrapper

isPrimitiveArrayType

public static boolean isPrimitiveArrayType(java.lang.String typeName)

Convenience method to return if the passed type (name) is a primitive array type.

Parameters:

typeName - Name of the type

Returns:

Whether it is a primitive array

isPrimitiveType

public static boolean isPrimitiveType(java.lang.String typeName)

Convenience method to return if the passed type (name) is a primitive type.

Parameters:

typeName - Name of the type

Returns:

Whether it is a primitive

convertValue

public static java.lang.Object convertValue(java.lang.Object value,
                                            java.lang.Class cls)

Convenience method to convert the passed value to an object of the specified type (if possible). If no such conversion is supported will return null. If the required type is a primitive will return an object of the wrapper type.

Parameters:

value - The value

cls - The class

Returns:

The converted value (or null)

typesAreCompatible

public static boolean typesAreCompatible(java.lang.Class cls1,
                                         java.lang.String clsName2,
                                         ClassLoaderResolver clr)

Convenience method to return if two types are compatible. Returns true if both types are primitive/wrappers and are of the same type. Returns true if clsName2 is the same or a subclass of cls1. Otherwise returns false;

Parameters:

cls1 - First class

clsName2 - Name of the second class

clr - ClassLoader resolver to use

Returns:

Whether they are compatible

typesAreCompatible

public static boolean typesAreCompatible(java.lang.Class cls1,
                                         java.lang.Class cls2)

Convenience method to return if two types are compatible. Returns true if both types are primitive/wrappers and are of the same type. Returns true if cls2 is the same or a subclass of cls1. Otherwise returns false;

Parameters:

cls1 - First class

cls2 - Second class

Returns:

Whether they are compatible

createFullClassName

public static java.lang.String createFullClassName(java.lang.String pkg_name,
                                                   java.lang.String cls_name)

Utility to create the full class name given the package and class name. Some examples

 packageName=test className=Test, returns result=test.Test
 packageName=test className=test1.Test, returns result=test1.Test
 packageName=<null> className=Test, returns result=Test
 packageName=<null> className=test1.Test, returns result=test1.Test
 

Parameters:

pkg_name - package name.

cls_name - class name.

Returns:

generated full class name.

getJavaLangClassForType

public static java.lang.String getJavaLangClassForType(java.lang.String type)

Convenience method to return the passed type as a java.lang type wherever possible. The passed type will be stripped of any package name and will be checked if it is a known java.lang class. This is used where the user has specified a class name for a collection or map element/key/value type and meant a java.lang class but didn't fully qualify it.

Parameters:

type - The type name

Returns:

The java.lang equivalent (or the input type if not possible)

classesAreDescendents

public static boolean classesAreDescendents(ClassLoaderResolver clr,
                                            java.lang.String class_name_1,
                                            java.lang.String class_name_2)

Method to check if 2 classes are direct descendents. So one of them is a superclass of the other.

Parameters:

clr - ClassLoaderResolver for loading the classes

class_name_1 - Name of first class

class_name_2 - Name of second class

Returns:

Whether they are direct descendents.

dumpClassInformation

public static void dumpClassInformation(java.lang.Class cls)

Utility to use Reflection to dump out the details of a class. Will list all superclasses, interfaces, methods and fields. Can be used, for example, in checking the methods adding by the enhancement process. The information is dumped out the JPOX GENERAL log.

Parameters:

cls - The class to dump out to the log

getJavaBeanGetterName

public static java.lang.String getJavaBeanGetterName(java.lang.String fieldName,
                                                     boolean isBoolean)

Generate a JavaBeans compatible getter name

Parameters:

fieldName - the field name

isBoolean - whether the field is primitive boolean type

Returns:

the getter name

getJavaBeanSetterName

public static java.lang.String getJavaBeanSetterName(java.lang.String fieldName)

Generate a JavaBeans compatible setter name

Parameters:

fieldName - the field name

Returns:

the setter name

getFieldNameForJavaBeanGetter

public static java.lang.String getFieldNameForJavaBeanGetter(java.lang.String methodName)

Generate a field name for JavaBeans compatible getter method

Parameters:

methodName - the method name

Returns:

the field name

getFieldNameForJavaBeanSetter

public static java.lang.String getFieldNameForJavaBeanSetter(java.lang.String methodName)

Generate a field name for JavaBeans compatible setter method

Parameters:

methodName - the method name

Returns:

the field name

getClassNameForFileURL

public static java.lang.String getClassNameForFileURL(java.net.URL fileURL)
                                               throws java.lang.ClassNotFoundException

Utility to find the class name of a class given the absolute file name of its class file. Creates a loader and loads the class directly to find it.

Parameters:

fileURL - URL for the class file

Returns:

The name of the class

Throws:

java.lang.ClassNotFoundException - Thrown when the file is not found

getPackageNameForClass

public static java.lang.String getPackageNameForClass(java.lang.Class cls)

Utility to return the package name for a class. Allows for the result of class.getPackage() being null.

Parameters:

cls - The class

Returns:

The name of its package (or null if no package e.g a primitive)

getClassNameForClass

public static java.lang.String getClassNameForClass(java.lang.Class cls)

Utility to return the class name without the package name for a class.

Parameters:

cls - The class

Returns:

The name of the class without its package

getCollectionElementType

public static java.lang.String getCollectionElementType(java.lang.reflect.Field field)

Convenience method to extract the element type of a collection when using JDK1.5 generics given the input field.

Parameters:

field - The field

Returns:

The name of the element class

getCollectionElementType

public static java.lang.String getCollectionElementType(java.lang.Class type,
                                                        java.lang.reflect.Type genericType)

Convenience method to extract the element type of a collection when using JDK1.5 generics given the input field.

Parameters:

type - the field type

genericType - the generic type

Returns:

The name of the element class

getCollectionElementType

public static java.lang.String getCollectionElementType(java.lang.reflect.Method method)

Convenience method to extract the element type of a collection when using JDK1.5 generics, given the input method (getter).

Parameters:

method - The method

Returns:

The name of the element class

getMapKeyType

public static java.lang.String getMapKeyType(java.lang.reflect.Field field)

Convenience method to extract the key type of a map when using JDK1.5 generics given the input field.

Parameters:

field - The field

Returns:

The name of the key class

getMapKeyType

public static java.lang.String getMapKeyType(java.lang.Class type,
                                             java.lang.reflect.Type genericType)

Convenience method to extract the key type of a map when using JDK1.5 generics given the input field.

Parameters:

type - the field type

genericType - the generic type

Returns:

The name of the key class

getMapKeyType

public static java.lang.String getMapKeyType(java.lang.reflect.Method method)

Convenience method to extract the key type of a map when using JDK1.5 generics given the input method.

Parameters:

method - The method

Returns:

The name of the key class

getMapValueType

public static java.lang.String getMapValueType(java.lang.reflect.Field field)

Convenience method to extract the value type of a map when using JDK1.5 generics given the input field

Parameters:

field - The field

Returns:

The name of the value class

getMapValueType

public static java.lang.String getMapValueType(java.lang.Class type,
                                               java.lang.reflect.Type genericType)

Convenience method to extract the value type of a map when using JDK1.5 generics given the input field

Parameters:

type - the field type

genericType - the generic type

Returns:

The name of the value class

getMapValueType

public static java.lang.String getMapValueType(java.lang.reflect.Method method)

Convenience method to extract the value type of a map when using JDK1.5 generics given the input method.

Parameters:

method - The method

Returns:

The name of the value class

getModifiersForFieldOfClass

public static int getModifiersForFieldOfClass(ClassLoaderResolver clr,
                                              java.lang.String className,
                                              java.lang.String fieldName)

Convenience accessor for the modifiers of a field in a class.

Parameters:

clr - ClassLoader resolver

className - Name of the class

fieldName - Name of the field

Returns:

The modifiers

isReferenceType

public static boolean isReferenceType(java.lang.Class cls)

Method to return whether the passes type is a "reference" type. A "reference" type is either an interface or an Object, so can be used as a reference to a persistable object.

Parameters:

cls - The type

Returns:

Whether it is a reference type

assertClassForJarExistsInClasspath

public static void assertClassForJarExistsInClasspath(ClassLoaderResolver clr,
                                                      java.lang.String className,
                                                      java.lang.String jarName)

Convenience method to throw a NucleusUserException if the specified class is not loadable from the ClassLoaderResolver.

Parameters:

clr - ClassLoader resolver

className - Name of the class

jarName - Name of the jar containing the class

Throws:

NucleusUserException - if the class is not found

stringArrayContainsValue

public static boolean stringArrayContainsValue(java.lang.String[] array,
                                               java.lang.String value)

Convenience method to return if a String array contains a value.

Parameters:

array - The String array

value - The value

Returns:

Whether it is contained

getValueOfMethodByReflection

public static java.lang.Object getValueOfMethodByReflection(java.lang.Object object,
                                                            java.lang.String methodName,
                                                            java.lang.Object... args)

Helper method to return the value returned by a method on an object using reflection.

Parameters:

object - The object

methodName - Name of the method

Returns:

The value

getValueOfFieldByReflection

public static java.lang.Object getValueOfFieldByReflection(java.lang.Object object,
                                                           java.lang.String fieldName)

Helper method to return the value of a field of an object using reflection.

Parameters:

object - The object

fieldName - Name of the field

Returns:

The value

getValueForIdentityField

public static java.lang.Object getValueForIdentityField(java.lang.Object id,
                                                        java.lang.String fieldName)

Method to find the value of a field of the provided user-defined identity. The field has to be either accessible, or have a Java-bean style getter.

Parameters:

id - The identity

fieldName - Name of the field

Returns:

The value of the field in this identity

Throws:

NucleusUserException - if not possible to get the value

getClassForMemberOfClass

public static java.lang.Class getClassForMemberOfClass(java.lang.Class cls,
                                                       java.lang.String memberName)

Method that returns the class type of a member of the specified class (if present). The member can either be a field, or a Java bean name (for a getter).

Parameters:

cls - The class

memberName - The member name

Returns:

The member class (or null if not present)