org.springframework.data.util

Class ReflectionUtils

java.lang.Object

org.springframework.data.util.ReflectionUtils

public final class ReflectionUtils
extends Object

Spring Data specific reflection utility methods and classes.

Since:

1.5

Author:

Oliver Gierke, Thomas Darimont, Christoph Strobl, Mark Paluch, Johannes Englmeier

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReflectionUtils.AnnotationFieldFilter A ReflectionUtils.FieldFilter for a given annotation.
static interface	ReflectionUtils.DescribedFieldFilter A ReflectionUtils.FieldFilter that has a description.

Method Summary

Modifier and Type	Method and Description
static <T> T	createInstanceIfPresent(String classname, T defaultInstance) Creates an instance of the class with the given fully qualified name or returns the given default instance if the class cannot be loaded or instantiated.
static Optional<Constructor<?>>	findConstructor(Class<?> type, Object... constructorArguments) Finds a constructor on the given type that matches the given constructor arguments.
static Field	findField(Class<?> type, ReflectionUtils.DescribedFieldFilter filter) Finds the field matching the given ReflectionUtils.DescribedFieldFilter.
static Field	findField(Class<?> type, ReflectionUtils.DescribedFieldFilter filter, boolean enforceUniqueness) Finds the field matching the given ReflectionUtils.DescribedFieldFilter.
static Field	findField(Class<?> type, ReflectionUtils.FieldFilter filter) Finds the first field on the given class matching the given ReflectionUtils.FieldFilter.
static Field	findRequiredField(Class<?> type, String name) Finds the field of the given name on the given type.
static Method	findRequiredMethod(Class<?> type, String name, Class<?>... parameterTypes) Returns the method with the given name of the given class and parameter types.
static Optional<Method>	getMethod(Class<?> type, String name, ResolvableType... parameterTypes) Returns the Method with the given name and parameters declared on the given type, if available.
static Object	getPrimitiveDefault(Class<?> type) Get default value for a primitive type.
static boolean	isKotlinClass(Class<?> type) Deprecated. since 2.3, use KotlinDetector.isKotlinType(Class) instead.
static boolean	isNullable(MethodParameter parameter) Returns whether the given MethodParameter is nullable.
static boolean	isSupportedKotlinClass(Class<?> type) Deprecated. since 2.3, use KotlinReflectionUtils.isSupportedKotlinClass(Class) instead.
static boolean	isVoid(Class<?> type) Check whether the given type represents a void type such as void, Void or Kotlin Unit.
static Class<?>	loadIfPresent(String name, ClassLoader classLoader) Loads the class with the given name using the given ClassLoader.
static Stream<Class<?>>	returnTypeAndParameters(Method method) Returns a Stream of the return and parameters types of the given Method.
static void	setField(Field field, Object target, Object value) Sets the given field on the given object to the given value.

Methods inherited from class java.lang.Object

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

Method Detail

createInstanceIfPresent

public static <T> T createInstanceIfPresent(String classname,
                                            T defaultInstance)

Creates an instance of the class with the given fully qualified name or returns the given default instance if the class cannot be loaded or instantiated.

Parameters:

classname - the fully qualified class name to create an instance for.

defaultInstance - the instance to fall back to in case the given class cannot be loaded or instantiated.

Returns:

isVoid

public static boolean isVoid(Class<?> type)

Check whether the given type represents a void type such as void, Void or Kotlin Unit.

Parameters:

type - must not be null.

Returns:

whether the given the type is a void type.

Since:

2.4

findField

@Nullable
public static Field findField(Class<?> type,
                                        ReflectionUtils.FieldFilter filter)

Finds the first field on the given class matching the given ReflectionUtils.FieldFilter.

Parameters:

type - must not be null.

filter - must not be null.

Returns:

the field matching the filter or null in case no field could be found.

findField

@Nullable
public static Field findField(Class<?> type,
                                        ReflectionUtils.DescribedFieldFilter filter)

Finds the field matching the given ReflectionUtils.DescribedFieldFilter. Will make sure there's only one field matching the filter.

Parameters:

type - must not be null.

filter - must not be null.

Returns:

the field matching the given ReflectionUtils.DescribedFieldFilter or null if none found.

Throws:

IllegalStateException - in case more than one matching field is found

See Also:

findField(Class, DescribedFieldFilter, boolean)

findField

@Nullable
public static Field findField(Class<?> type,
                                        ReflectionUtils.DescribedFieldFilter filter,
                                        boolean enforceUniqueness)

Finds the field matching the given ReflectionUtils.DescribedFieldFilter. Will make sure there's only one field matching the filter in case enforceUniqueness is true.

Parameters:

type - must not be null.

filter - must not be null.

enforceUniqueness - whether to enforce uniqueness of the field

Returns:

the field matching the given ReflectionUtils.DescribedFieldFilter or null if none found.

Throws:

IllegalStateException - if enforceUniqueness is true and more than one matching field is found

findRequiredField

public static Field findRequiredField(Class<?> type,
                                      String name)

Finds the field of the given name on the given type.

Parameters:

type - must not be null.

name - must not be null or empty.

Returns:

Throws:

IllegalArgumentException - in case the field can't be found.

setField

public static void setField(Field field,
                            Object target,
                            @Nullable
                            Object value)

Sets the given field on the given object to the given value. Will make sure the given field is accessible.

Parameters:

field - must not be null.

target - must not be null.

value -

findConstructor

public static Optional<Constructor<?>> findConstructor(Class<?> type,
                                                       Object... constructorArguments)

Finds a constructor on the given type that matches the given constructor arguments.

Parameters:

type - must not be null.

constructorArguments - must not be null.

Returns:

a Constructor that is compatible with the given arguments.

findRequiredMethod

public static Method findRequiredMethod(Class<?> type,
                                        String name,
                                        Class<?>... parameterTypes)

Returns the method with the given name of the given class and parameter types. Prefers regular methods over bridge and synthetic ones.

Parameters:

type - must not be null.

name - must not be null.

parameterTypes - must not be null.

Returns:

the method object.

Throws:

IllegalArgumentException - in case the method cannot be resolved.

returnTypeAndParameters

public static Stream<Class<?>> returnTypeAndParameters(Method method)

Returns a Stream of the return and parameters types of the given Method.

Parameters:

method - must not be null.

Returns:

Since:

2.0

getMethod

public static Optional<Method> getMethod(Class<?> type,
                                         String name,
                                         ResolvableType... parameterTypes)

Returns the Method with the given name and parameters declared on the given type, if available.

Parameters:

type - must not be null.

name - must not be null or empty.

parameterTypes - must not be null.

Returns:

Since:

2.0

isKotlinClass

@Deprecated
public static boolean isKotlinClass(Class<?> type)

Deprecated. since 2.3, use KotlinDetector.isKotlinType(Class) instead.

Return true if the specified class is a Kotlin one.

Returns:

true if type is a Kotlin class.

Since:

2.0

isSupportedKotlinClass

@Deprecated
public static boolean isSupportedKotlinClass(Class<?> type)

Deprecated. since 2.3, use KotlinReflectionUtils.isSupportedKotlinClass(Class) instead.

Return true if the specified class is a supported Kotlin class. Currently supported are only regular Kotlin classes. Other class types (synthetic, SAM, lambdas) are not supported via reflection.

Returns:

true if type is a supported Kotlin class.

Since:

2.0

isNullable

public static boolean isNullable(MethodParameter parameter)

Returns whether the given MethodParameter is nullable. Nullable parameters are reference types and ones that are defined in Kotlin as such.

Returns:

true if MethodParameter is nullable.

Since:

2.0

getPrimitiveDefault

public static Object getPrimitiveDefault(Class<?> type)

Get default value for a primitive type.

Parameters:

type - must not be null.

Returns:

boxed primitive default value.

Since:

2.1

loadIfPresent

@Nullable
public static Class<?> loadIfPresent(String name,
                                               ClassLoader classLoader)

Loads the class with the given name using the given ClassLoader.

Parameters:

name - the name of the class to be loaded.

classLoader - the ClassLoader to use to load the class.

Returns:

the Class or null in case the class can't be loaded for any reason.

Since:

2.5