org.junit.platform.commons.util

Class ReflectionUtils

java.lang.Object

org.junit.platform.commons.util.ReflectionUtils

@API(value=Internal)
public final class ReflectionUtils
extends java.lang.Object

Collection of utilities for working with the Java reflection APIs.

DISCLAIMER

These utilities are intended solely for usage within the JUnit framework itself. Any usage by external parties is not supported. Use at your own risk!

Since:

1.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReflectionUtils.MethodSortOrder

Method Summary

Modifier and Type	Method and Description
static java.util.List<java.lang.Class<?>>	findAllClassesInClasspathRoot(java.io.File root, java.util.function.Predicate<java.lang.Class<?>> classTester)
static java.util.List<java.lang.Class<?>>	findAllClassesInPackage(java.lang.String basePackageName, java.util.function.Predicate<java.lang.Class<?>> classTester)
static java.util.Optional<java.lang.reflect.Method>	findMethod(java.lang.Class<?> clazz, java.lang.String methodName, java.lang.Class<?>... parameterTypes)
static java.util.List<java.lang.reflect.Method>	findMethods(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Method> predicate)
static java.util.List<java.lang.reflect.Method>	findMethods(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Method> predicate, ReflectionUtils.MethodSortOrder sortOrder)
static java.util.List<java.lang.Class<?>>	findNestedClasses(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.Class<?>> predicate)
static java.util.Set<java.lang.Class<?>>	getAllAssignmentCompatibleClasses(java.lang.Class<?> clazz) Return all classes and interfaces that can be used as assignment types for instances of the specified Class, including itself.
static java.util.Set<java.io.File>	getAllClasspathRootDirectories()
static <T> java.lang.reflect.Constructor<T>	getDeclaredConstructor(java.lang.Class<T> clazz) Get the sole declared Constructor for the supplied class.
static java.lang.ClassLoader	getDefaultClassLoader()
static java.util.Optional<java.lang.reflect.Method>	getMethod(java.lang.Class<?> clazz, java.lang.String methodName, java.lang.Class<?>... parameterTypes)
static java.util.Optional<java.lang.Object>	getOuterInstance(java.lang.Object inner, java.lang.Class<?> targetType)
static java.lang.Class<?>	getWrapperType(java.lang.Class<?> type) Get the wrapper type for the supplied primitive type.
static java.lang.Object	invokeMethod(java.lang.reflect.Method method, java.lang.Object target, java.lang.Object... args) Invoke the supplied method, making it accessible if necessary and masking any checked exception as an unchecked exception.
static boolean	isAbstract(java.lang.Class<?> clazz)
static boolean	isAbstract(java.lang.reflect.Member member)
static boolean	isArray(java.lang.Object obj) Determine if the supplied object is an array.
static boolean	isAssignableTo(java.lang.Object obj, java.lang.Class<?> type) Determine if the supplied object can be assigned to the supplied type for the purpose of reflective method invocations.
static boolean	isPackage(java.lang.String packageName)
static boolean	isPrivate(java.lang.Class<?> clazz)
static boolean	isPrivate(java.lang.reflect.Member member)
static boolean	isPublic(java.lang.Class<?> clazz)
static boolean	isPublic(java.lang.reflect.Member member)
static boolean	isStatic(java.lang.Class<?> clazz)
static boolean	isStatic(java.lang.reflect.Member member)
static java.util.Optional<java.lang.Class<?>>	loadClass(java.lang.String name) Load a class by its fully qualified name.
static java.util.Optional<java.lang.Class<?>>	loadClass(java.lang.String name, java.lang.ClassLoader classLoader) Load a class by its fully qualified name, using the supplied ClassLoader.
static java.util.Optional<java.lang.reflect.Method>	loadMethod(java.lang.String fullyQualifiedMethodName) Load a method by its fully qualified name.
static <T> T	newInstance(java.lang.Class<T> clazz, java.lang.Object... args) Create a new instance of the specified Class by invoking the constructor whose argument list matches the types of the supplied arguments.
static <T> T	newInstance(java.lang.reflect.Constructor<T> constructor, java.lang.Object... args) Create a new instance of type T by invoking the supplied constructor with the supplied arguments.
static <T> java.util.Optional<java.lang.Object>	readFieldValue(java.lang.Class<T> clazz, java.lang.String fieldName, T instance) Read the value of a potentially inaccessible field.

Methods inherited from class java.lang.Object

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

Method Detail

getDefaultClassLoader

public static java.lang.ClassLoader getDefaultClassLoader()

isPublic

public static boolean isPublic(java.lang.Class<?> clazz)

isPublic

public static boolean isPublic(java.lang.reflect.Member member)

isPrivate

public static boolean isPrivate(java.lang.Class<?> clazz)

isPrivate

public static boolean isPrivate(java.lang.reflect.Member member)

isAbstract

public static boolean isAbstract(java.lang.Class<?> clazz)

isAbstract

public static boolean isAbstract(java.lang.reflect.Member member)

isStatic

public static boolean isStatic(java.lang.Class<?> clazz)

isStatic

public static boolean isStatic(java.lang.reflect.Member member)

isArray

public static boolean isArray(java.lang.Object obj)

Determine if the supplied object is an array.

Parameters:

obj - the object to test; potentially null

Returns:

true if the object is an array

isAssignableTo

public static boolean isAssignableTo(java.lang.Object obj,
                                     java.lang.Class<?> type)

Determine if the supplied object can be assigned to the supplied type for the purpose of reflective method invocations.

In contrast to Class.isInstance(Object), this method returns true if the supplied type represents a primitive type whose wrapper matches the supplied object's type.

Returns true if the supplied object is null and the supplied type does not represent a primitive type.

Parameters:

obj - the object to test for assignment compatibility; potentially null

type - the type to check against; never null

Returns:

true if the object is assignment compatible

See Also:

Class.isInstance(Object), Class.isAssignableFrom(Class)

getWrapperType

public static java.lang.Class<?> getWrapperType(java.lang.Class<?> type)

Get the wrapper type for the supplied primitive type.

Parameters:

type - the primitive type for which to retrieve the wrapper type

Returns:

the corresponding wrapper type or null if the supplied type is null or not a primitive type

newInstance

public static <T> T newInstance(java.lang.Class<T> clazz,
                                java.lang.Object... args)

Create a new instance of the specified Class by invoking the constructor whose argument list matches the types of the supplied arguments.

The constructor will be made accessible if necessary, and any checked exception will be masked as an unchecked exception.

Parameters:

clazz - the class to instantiate; never null

args - the arguments to pass to the constructor none of which may be null

Returns:

the new instance

See Also:

newInstance(Constructor, Object...), ExceptionUtils.throwAsUncheckedException(Throwable)

newInstance

public static <T> T newInstance(java.lang.reflect.Constructor<T> constructor,
                                java.lang.Object... args)

Create a new instance of type T by invoking the supplied constructor with the supplied arguments.

The constructor will be made accessible if necessary, and any checked exception will be masked as an unchecked exception.

Parameters:

constructor - the constructor to invoke; never null

args - the arguments to pass to the constructor

Returns:

the new instance; never null

See Also:

newInstance(Class, Object...), ExceptionUtils.throwAsUncheckedException(Throwable)

invokeMethod

public static java.lang.Object invokeMethod(java.lang.reflect.Method method,
                                            java.lang.Object target,
                                            java.lang.Object... args)

Invoke the supplied method, making it accessible if necessary and masking any checked exception as an unchecked exception.

Parameters:

method - the method to invoke; never null

target - the object on which to invoke the method; may be null if the method is static

args - the arguments to pass to the method

Returns:

the value returned by the method invocation or null if the return type is void

See Also:

ExceptionUtils.throwAsUncheckedException(Throwable)

loadClass

public static java.util.Optional<java.lang.Class<?>> loadClass(java.lang.String name)

Load a class by its fully qualified name.

Parameters:

name - the fully qualified name of the class to load; never null or blank

See Also:

loadClass(String, ClassLoader)

loadClass

public static java.util.Optional<java.lang.Class<?>> loadClass(java.lang.String name,
                                                               java.lang.ClassLoader classLoader)

Load a class by its fully qualified name, using the supplied ClassLoader.

Parameters:

name - the fully qualified name of the class to load; never null or blank

classLoader - the ClassLoader to use; never null

See Also:

loadClass(String)

loadMethod

public static java.util.Optional<java.lang.reflect.Method> loadMethod(java.lang.String fullyQualifiedMethodName)

Load a method by its fully qualified name.

The supported format is [fully qualified class name]#[methodName]. For example, the fully qualified name for the chars() method in java.lang.String is java.lang.String#chars.

Parameters:

fullyQualifiedMethodName - the fully qualified name of the method to load; never null or blank

Returns:

Optional of Method

getOuterInstance

public static java.util.Optional<java.lang.Object> getOuterInstance(java.lang.Object inner,
                                                                    java.lang.Class<?> targetType)

isPackage

public static boolean isPackage(java.lang.String packageName)

getAllClasspathRootDirectories

public static java.util.Set<java.io.File> getAllClasspathRootDirectories()

findAllClassesInClasspathRoot

public static java.util.List<java.lang.Class<?>> findAllClassesInClasspathRoot(java.io.File root,
                                                                               java.util.function.Predicate<java.lang.Class<?>> classTester)

findAllClassesInPackage

public static java.util.List<java.lang.Class<?>> findAllClassesInPackage(java.lang.String basePackageName,
                                                                         java.util.function.Predicate<java.lang.Class<?>> classTester)

findNestedClasses

public static java.util.List<java.lang.Class<?>> findNestedClasses(java.lang.Class<?> clazz,
                                                                   java.util.function.Predicate<java.lang.Class<?>> predicate)

getDeclaredConstructor

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

Get the sole declared Constructor for the supplied class.

Throws a PreconditionViolationException if the supplied class declares more than one constructor.

Parameters:

clazz - the class to get the constructor for

Returns:

the sole declared constructor; never null

See Also:

Class.getDeclaredConstructors()

getMethod

public static java.util.Optional<java.lang.reflect.Method> getMethod(java.lang.Class<?> clazz,
                                                                     java.lang.String methodName,
                                                                     java.lang.Class<?>... parameterTypes)

findMethod

public static java.util.Optional<java.lang.reflect.Method> findMethod(java.lang.Class<?> clazz,
                                                                      java.lang.String methodName,
                                                                      java.lang.Class<?>... parameterTypes)

findMethods

public static java.util.List<java.lang.reflect.Method> findMethods(java.lang.Class<?> clazz,
                                                                   java.util.function.Predicate<java.lang.reflect.Method> predicate)

findMethods

public static java.util.List<java.lang.reflect.Method> findMethods(java.lang.Class<?> clazz,
                                                                   java.util.function.Predicate<java.lang.reflect.Method> predicate,
                                                                   ReflectionUtils.MethodSortOrder sortOrder)

readFieldValue

public static <T> java.util.Optional<java.lang.Object> readFieldValue(java.lang.Class<T> clazz,
                                                                      java.lang.String fieldName,
                                                                      T instance)

Read the value of a potentially inaccessible field.

If the field does not exist, an exception occurs while reading it, or the value of the field is null, an empty Optional is returned.

Parameters:

clazz - the class where the field is declared; never null

fieldName - the name of the field; never null or empty

instance - the instance from where the value is to be read; may be null for a static field

getAllAssignmentCompatibleClasses

public static java.util.Set<java.lang.Class<?>> getAllAssignmentCompatibleClasses(java.lang.Class<?> clazz)

Return all classes and interfaces that can be used as assignment types for instances of the specified Class, including itself.

Parameters:

clazz - the Class to lookup

See Also:

Class.isAssignableFrom(java.lang.Class<?>)