org.apache.logging.log4j.core.util

Class ReflectionUtil

java.lang.Object

org.apache.logging.log4j.core.util.ReflectionUtil

public final class ReflectionUtil
extends java.lang.Object

Utility class for performing common reflective operations.

Since:

2.1

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ReflectionUtil()

Method Summary

Modifier and Type	Method and Description
static <T> java.lang.reflect.Constructor<T>	getDefaultConstructor(java.lang.Class<T> clazz) Gets the default (no-arg) constructor for a given class.
static java.lang.Object	getFieldValue(java.lang.reflect.Field field, java.lang.Object instance) Gets the value of a Field, making it accessible if required.
static java.lang.Object	getStaticFieldValue(java.lang.reflect.Field field) Gets the value of a static Field, making it accessible if required.
static <T> T	instantiate(java.lang.Class<T> clazz) Constructs a new T object using the default constructor of its class.
static <T extends java.lang.reflect.AccessibleObject & java.lang.reflect.Member> boolean	isAccessible(T member) Indicates whether or not a Member is both public and is contained in a public class.
static void	makeAccessible(java.lang.reflect.Field field) Makes a Field accessible if it is not public or if it is final.
static <T extends java.lang.reflect.AccessibleObject & java.lang.reflect.Member> void	makeAccessible(T member) Makes a Member accessible if the member is not public.
static void	setFieldValue(java.lang.reflect.Field field, java.lang.Object instance, java.lang.Object value) Sets the value of a Field, making it accessible if required.
static void	setStaticFieldValue(java.lang.reflect.Field field, java.lang.Object value) Sets the value of a static Field, making it accessible if required.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectionUtil

private ReflectionUtil()

Method Detail

isAccessible

public static <T extends java.lang.reflect.AccessibleObject & java.lang.reflect.Member> boolean isAccessible(T member)

Indicates whether or not a Member is both public and is contained in a public class.

Type Parameters:

T - type of the object whose accessibility to test

Parameters:

member - the Member to check for public accessibility (must not be null).

Returns:

true if member is public and contained in a public class.

Throws:

java.lang.NullPointerException - if member is null.

makeAccessible

public static <T extends java.lang.reflect.AccessibleObject & java.lang.reflect.Member> void makeAccessible(T member)

Makes a Member accessible if the member is not public.

Type Parameters:

T - type of the object to make accessible

Parameters:

member - the Member to make accessible (must not be null).

Throws:

java.lang.NullPointerException - if member is null.

makeAccessible

public static void makeAccessible(java.lang.reflect.Field field)

Makes a Field accessible if it is not public or if it is final.

Note that using this method to make a final field writable will most likely not work very well due to compiler optimizations and the like.

Parameters:

field - the Field to make accessible (must not be null).

Throws:

java.lang.NullPointerException - if field is null.

getFieldValue

public static java.lang.Object getFieldValue(java.lang.reflect.Field field,
                                             java.lang.Object instance)

Gets the value of a Field, making it accessible if required.

Parameters:

field - the Field to obtain a value from (must not be null).

instance - the instance to obtain the field value from or null only if the field is static.

Returns:

the value stored by the field.

Throws:

java.lang.NullPointerException - if field is null, or if instance is null but field is not static.

See Also:

Field.get(Object)

getStaticFieldValue

public static java.lang.Object getStaticFieldValue(java.lang.reflect.Field field)

Gets the value of a static Field, making it accessible if required.

Parameters:

field - the Field to obtain a value from (must not be null).

Returns:

the value stored by the static field.

Throws:

java.lang.NullPointerException - if field is null, or if field is not static.

See Also:

Field.get(Object)

setFieldValue

public static void setFieldValue(java.lang.reflect.Field field,
                                 java.lang.Object instance,
                                 java.lang.Object value)

Sets the value of a Field, making it accessible if required.

Parameters:

field - the Field to write a value to (must not be null).

instance - the instance to write the value to or null only if the field is static.

value - the (possibly wrapped) value to write to the field.

Throws:

java.lang.NullPointerException - if field is null, or if instance is null but field is not static.

See Also:

Field.set(Object, Object)

setStaticFieldValue

public static void setStaticFieldValue(java.lang.reflect.Field field,
                                       java.lang.Object value)

Sets the value of a static Field, making it accessible if required.

Parameters:

field - the Field to write a value to (must not be null).

value - the (possibly wrapped) value to write to the field.

Throws:

java.lang.NullPointerException - if field is null, or if field is not static.

See Also:

Field.set(Object, Object)

getDefaultConstructor

public static <T> java.lang.reflect.Constructor<T> getDefaultConstructor(java.lang.Class<T> clazz)

Gets the default (no-arg) constructor for a given class.

Type Parameters:

T - the type made by the constructor

Parameters:

clazz - the class to find a constructor for

Returns:

the default constructor for the given class

Throws:

java.lang.IllegalStateException - if no default constructor can be found

instantiate

public static <T> T instantiate(java.lang.Class<T> clazz)

Constructs a new T object using the default constructor of its class. Any exceptions thrown by the constructor will be rethrown by this method, possibly wrapped in an UndeclaredThrowableException.

Type Parameters:

T - the type of the object to construct.

Parameters:

clazz - the class to use for instantiation.

Returns:

a new instance of T made from its default constructor.

Throws:

java.lang.IllegalArgumentException - if the given class is abstract, an interface, an array class, a primitive type, or void

java.lang.IllegalStateException - if access is denied to the constructor, or there are no default constructors