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

java.lang.Object
  org.apache.logging.log4j.core.util.ReflectionUtil

public final class ReflectionUtil
extends Object

Utility class for performing common reflective operations.

Since:

2.1

Method Summary

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

Method Detail

isAccessible

public static <T extends AccessibleObject & Member> boolean isAccessible(T member)

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

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:

NullPointerException - if member is null.

makeAccessible

public static <T extends AccessibleObject & Member> void makeAccessible(T member)

Makes a Member accessible if the member is not public.

Parameters:

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

Throws:

NullPointerException - if member is null.

makeAccessible

public static void makeAccessible(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:

NullPointerException - if field is null.

getFieldValue

public static Object getFieldValue(Field field,
                                   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:

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

See Also:

Field.get(Object)

getStaticFieldValue

public static Object getStaticFieldValue(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:

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

See Also:

Field.get(Object)

setFieldValue

public static void setFieldValue(Field field,
                                 Object instance,
                                 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:

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(Field field,
                                       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:

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

See Also:

Field.set(Object, Object)

getDefaultConstructor

public static <T> Constructor<T> getDefaultConstructor(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:

IllegalStateException - if no default constructor can be found

instantiate

public static <T> T instantiate(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:

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

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