Package org.junit.platform.commons.util

Class ReflectionUtils


  • @API(status=INTERNAL,
     since="1.0")
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!

    Some utilities are published via the maintained ReflectionSupport class.

    Since:
    1.0
    See Also:
    ReflectionSupport

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  ReflectionUtils.HierarchyTraversalMode
      Modes in which a hierarchy can be traversed — for example, when searching for methods or fields within a class hierarchy.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static java.util.List<java.lang.Class<?>> findAllClassesInClasspathRoot​(java.net.URI root, java.util.function.Predicate<java.lang.Class<?>> classFilter, java.util.function.Predicate<java.lang.String> classNameFilter)  
      static java.util.List<java.lang.Class<?>> findAllClassesInClasspathRoot​(java.net.URI root, ClassFilter classFilter)  
      static java.util.List<java.lang.Class<?>> findAllClassesInPackage​(java.lang.String basePackageName, java.util.function.Predicate<java.lang.Class<?>> classFilter, java.util.function.Predicate<java.lang.String> classNameFilter)  
      static java.util.List<java.lang.Class<?>> findAllClassesInPackage​(java.lang.String basePackageName, ClassFilter classFilter)  
      static java.util.List<java.lang.reflect.Constructor<?>> findConstructors​(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Constructor<?>> predicate)
      Find all constructors in the supplied class that match the supplied predicate.
      static java.util.List<java.lang.reflect.Field> findFields​(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Field> predicate, ReflectionUtils.HierarchyTraversalMode traversalMode)
      Find all fields of the supplied class or interface that match the specified predicate.
      static java.util.Optional<java.lang.reflect.Method> findMethod​(java.lang.Class<?> clazz, java.lang.String methodName, java.lang.Class<?>... parameterTypes)  
      static java.util.Optional<java.lang.reflect.Method> findMethod​(java.lang.Class<?> clazz, java.lang.String methodName, java.lang.String parameterTypeNames)  
      static java.util.List<java.lang.reflect.Method> findMethods​(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Method> predicate)
      Find all methods of the supplied class or interface that match the specified predicate, using top-down search semantics within the type hierarchy.
      static java.util.List<java.lang.reflect.Method> findMethods​(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Method> predicate, ReflectionUtils.HierarchyTraversalMode traversalMode)  
      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.nio.file.Path> 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.String getFullyQualifiedMethodName​(java.lang.Class<?> clazz, java.lang.String methodName, java.lang.Class<?>... parameterTypes)
      Build the fully qualified method name for the method described by the supplied class, method name, and parameter types.
      static java.util.Optional<java.lang.Object> getOutermostInstance​(java.lang.Object inner, java.lang.Class<?> requiredType)
      Get the outermost instance of the required type, searching recursively through enclosing instances.
      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)  
      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 isInnerClass​(java.lang.Class<?> clazz)  
      static boolean isMethodPresent​(java.lang.Class<?> clazz, java.util.function.Predicate<java.lang.reflect.Method> predicate)
      Determine if a Method matching the supplied Predicate is present within the type hierarchy of the specified class, beginning with the specified class or interface and traversing up the type hierarchy until such a method is found or the type hierarchy is exhausted.
      static boolean isNotPrivate​(java.lang.reflect.Member member)  
      static boolean isNotStatic​(java.lang.reflect.Member member)  
      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)  
      static java.util.Optional<java.lang.Class<?>> loadClass​(java.lang.String name, java.lang.ClassLoader classLoader)
      Load a class by its primitive name or fully qualified name, using the supplied ClassLoader.
      static <T extends java.lang.reflect.AccessibleObject>
      T      		 makeAccessible​(T object)  
      static <T> T newInstance​(java.lang.Class<T> clazz, java.lang.Object... args)  
      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 or nonexistent field.
      static java.util.Optional<java.lang.Object> readFieldValue​(java.lang.reflect.Field field)
      Read the value of a potentially inaccessible static field.
      static <T> java.util.Optional<java.lang.Object> readFieldValue​(java.lang.reflect.Field field, T instance)
      Read the value of a potentially inaccessible field.
      static boolean returnsVoid​(java.lang.reflect.Method method)  

      • Methods inherited from class java.lang.Object

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

    • Method Detail

      • 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)

      • isNotPrivate

        public static boolean isNotPrivate​(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)

      • isNotStatic

        public static boolean isNotStatic​(java.lang.reflect.Member member)

      • isInnerClass

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

      • returnsVoid

        public static boolean returnsVoid​(java.lang.reflect.Method method)

      • 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.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)

      • 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 or nonexistent 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
        See Also:
        readFieldValue(Field), readFieldValue(Field, Object)

      • readFieldValue

        public static java.util.Optional<java.lang.Object> readFieldValue​(java.lang.reflect.Field field)
        Read the value of a potentially inaccessible static field.

        If an exception occurs while reading the field or if the value of the field is null, an empty Optional is returned.

        Parameters:
        field - the field to read; never null
        See Also:
        readFieldValue(Field, Object), readFieldValue(Class, String, Object)

      • readFieldValue

        public static <T> java.util.Optional<java.lang.Object> readFieldValue​(java.lang.reflect.Field field,
                                                                      T instance)
        Read the value of a potentially inaccessible field.

        If an exception occurs while reading the field or if the value of the field is null, an empty Optional is returned.

        Parameters:
        field - the field to read; never null
        instance - the instance from which the value is to be read; may be null for a static field
        See Also:
        readFieldValue(Field), readFieldValue(Class, String, Object)

      • loadClass

        public static java.util.Optional<java.lang.Class<?>> loadClass​(java.lang.String name,
                                                               java.lang.ClassLoader classLoader)
        Load a class by its primitive name or fully qualified name, using the supplied ClassLoader.

        See ReflectionSupport.loadClass(String) for details on support for class names for arrays.

        Parameters:
        name - the name of the class to load; never null or blank
        classLoader - the ClassLoader to use; never null
        See Also:
        loadClass(String)

      • getFullyQualifiedMethodName

        public static java.lang.String getFullyQualifiedMethodName​(java.lang.Class<?> clazz,
                                                           java.lang.String methodName,
                                                           java.lang.Class<?>... parameterTypes)
        Build the fully qualified method name for the method described by the supplied class, method name, and parameter types.
        Parameters:
        clazz - the class that declares the method; never null
        methodName - the name of the method; never null or blank
        parameterTypes - the parameter types of the method; may be null or empty
        Returns:
        fully qualified method name; never null

      • getOutermostInstance

        public static java.util.Optional<java.lang.Object> getOutermostInstance​(java.lang.Object inner,
                                                                        java.lang.Class<?> requiredType)
        Get the outermost instance of the required type, searching recursively through enclosing instances.

        If the supplied inner object is of the required type, it will simply be returned.

        Parameters:
        inner - the inner object from which to begin the search; never null
        requiredType - the required type of the outermost instance; never null
        Returns:
        an Optional containing the outermost instance; never null but potentially empty

      • getAllClasspathRootDirectories

        public static java.util.Set<java.nio.file.Path> getAllClasspathRootDirectories​()

      • findAllClassesInClasspathRoot

        @API(status=INTERNAL,
     since="1.1")
public static java.util.List<java.lang.Class<?>> findAllClassesInClasspathRoot​(java.net.URI root,
                                                                               ClassFilter classFilter)

      • findAllClassesInPackage

        @API(status=INTERNAL,
     since="1.1")
public static java.util.List<java.lang.Class<?>> findAllClassesInPackage​(java.lang.String basePackageName,
                                                                         ClassFilter classFilter)

      • 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()

      • findConstructors

        public static java.util.List<java.lang.reflect.Constructor<?>> findConstructors​(java.lang.Class<?> clazz,
                                                                                java.util.function.Predicate<java.lang.reflect.Constructor<?>> predicate)
        Find all constructors in the supplied class that match the supplied predicate.
        Parameters:
        clazz - the class in which to search for constructors; never null
        predicate - the predicate to use to test for a match; never null
        Returns:
        an immutable list of all such constructors found; never null but potentially empty

      • findFields

        public static java.util.List<java.lang.reflect.Field> findFields​(java.lang.Class<?> clazz,
                                                                 java.util.function.Predicate<java.lang.reflect.Field> predicate,
                                                                 ReflectionUtils.HierarchyTraversalMode traversalMode)
        Find all fields of the supplied class or interface that match the specified predicate.

        The results will not contain fields that are hidden.

        Parameters:
        clazz - the class or interface in which to find the fields; never null
        predicate - the field filter; never null
        traversalMode - the hierarchy traversal mode; never null
        Returns:
        an immutable list of all such fields found; never null but potentially empty

      • isMethodPresent

        public static boolean isMethodPresent​(java.lang.Class<?> clazz,
                                      java.util.function.Predicate<java.lang.reflect.Method> predicate)
        Determine if a Method matching the supplied Predicate is present within the type hierarchy of the specified class, beginning with the specified class or interface and traversing up the type hierarchy until such a method is found or the type hierarchy is exhausted.
        Parameters:
        clazz - the class or interface in which to find the method; never null
        predicate - the predicate to use to test for a match; never null
        Returns:
        true if such a method is present
        See Also:
        findMethod(Class, String, String), findMethod(Class, String, Class...)

      • findMethods

        public static java.util.List<java.lang.reflect.Method> findMethods​(java.lang.Class<?> clazz,
                                                                   java.util.function.Predicate<java.lang.reflect.Method> predicate)
        Find all methods of the supplied class or interface that match the specified predicate, using top-down search semantics within the type hierarchy.

        The results will not contain instance methods that are overridden or static methods that are hidden.

        Parameters:
        clazz - the class or interface in which to find the methods; never null
        predicate - the method filter; never null
        Returns:
        an immutable list of all such methods found; never null
        See Also:
        ReflectionUtils.HierarchyTraversalMode.TOP_DOWN, findMethods(Class, Predicate, HierarchyTraversalMode)

      • makeAccessible

        public static <T extends java.lang.reflect.AccessibleObject> T makeAccessible​(T object)

      • 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 look up
        See Also:
        Class.isAssignableFrom(java.lang.Class<?>)