Module java.base
Package java.lang.reflect

Class Parameter

  • All Implemented Interfaces:
    AnnotatedElement

    public final class Parameter
extends Object
implements AnnotatedElement
    Information about method parameters. A Parameter provides information about method parameters, including its name and modifiers. It also provides an alternate means of obtaining attributes for the parameter.
    Since:
    1.8

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean equals​(Object obj)
      Compares based on the executable and the index.
      AnnotatedType getAnnotatedType​()
      Returns an AnnotatedType object that represents the use of a type to specify the type of the formal parameter represented by this Parameter.
      <T extends Annotation>
      T      		 getAnnotation​(Class<T> annotationClass)
      Returns this element's annotation for the specified type if such an annotation is present, else null.
      Annotation[] getAnnotations​()
      Returns annotations that are present on this element.
      <T extends Annotation>
      T[]      		 getAnnotationsByType​(Class<T> annotationClass)
      Returns annotations that are associated with this element.
      <T extends Annotation>
      T      		 getDeclaredAnnotation​(Class<T> annotationClass)
      Returns this element's annotation for the specified type if such an annotation is directly present, else null.
      Annotation[] getDeclaredAnnotations​()
      Returns annotations that are directly present on this element.
      <T extends Annotation>
      T[]      		 getDeclaredAnnotationsByType​(Class<T> annotationClass)
      Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present.
      Executable getDeclaringExecutable​()
      Return the Executable which declares this parameter.
      int getModifiers​()
      Get the modifier flags for this the parameter represented by this Parameter object.
      String getName​()
      Returns the name of the parameter.
      Type getParameterizedType​()
      Returns a Type object that identifies the parameterized type for the parameter represented by this Parameter object.
      Class<?> getType​()
      Returns a Class object that identifies the declared type for the parameter represented by this Parameter object.
      int hashCode​()
      Returns a hash code based on the executable's hash code and the index.
      boolean isImplicit​()
      Returns true if this parameter is implicitly declared in source code; returns false otherwise.
      boolean isNamePresent​()
      Returns true if the parameter has a name according to the class file; returns false otherwise.
      boolean isSynthetic​()
      Returns true if this parameter is neither implicitly nor explicitly declared in source code; returns false otherwise.
      boolean isVarArgs​()
      Returns true if this parameter represents a variable argument list; returns false otherwise.
      String toString​()
      Returns a string describing this parameter.

    • Method Detail

      • equals

        public boolean equals​(Object obj)
        Compares based on the executable and the index.
        Overrides:
        equals in class Object
        Parameters:
        obj - The object to compare.
        Returns:
        Whether or not this is equal to the argument.
        See Also:
        Object.hashCode(), HashMap

      • isNamePresent

        public boolean isNamePresent​()
        Returns true if the parameter has a name according to the class file; returns false otherwise. Whether a parameter has a name is determined by the MethodParameters attribute of the method which declares the parameter.
        Returns:
        true if and only if the parameter has a name according to the class file.

      • toString

        public String toString​()
        Returns a string describing this parameter. The format is the modifiers for the parameter, if any, in canonical order as recommended by The Java™ Language Specification, followed by the fully- qualified type of the parameter (excluding the last [] if the parameter is variable arity), followed by "..." if the parameter is variable arity, followed by a space, followed by the name of the parameter.
        Overrides:
        toString in class Object
        Returns:
        A string representation of the parameter and associated information.

      • getDeclaringExecutable

        public Executable getDeclaringExecutable​()
        Return the Executable which declares this parameter.
        Returns:
        The Executable declaring this parameter.

      • getModifiers

        public int getModifiers​()
        Get the modifier flags for this the parameter represented by this Parameter object.
        Returns:
        The modifier flags for this parameter.

      • getName

        public String getName​()
        Returns the name of the parameter. If the parameter's name is present, then this method returns the name provided by the class file. Otherwise, this method synthesizes a name of the form argN, where N is the index of the parameter in the descriptor of the method which declares the parameter.
        Returns:
        The name of the parameter, either provided by the class file or synthesized if the class file does not provide a name.

      • getParameterizedType

        public Type getParameterizedType​()
        Returns a Type object that identifies the parameterized type for the parameter represented by this Parameter object.
        Returns:
        a Type object identifying the parameterized type of the parameter represented by this object

      • getType

        public Class<?> getType​()
        Returns a Class object that identifies the declared type for the parameter represented by this Parameter object.
        Returns:
        a Class object identifying the declared type of the parameter represented by this object

      • getAnnotatedType

        public AnnotatedType getAnnotatedType​()
        Returns an AnnotatedType object that represents the use of a type to specify the type of the formal parameter represented by this Parameter.
        Returns:
        an AnnotatedType object representing the use of a type to specify the type of the formal parameter represented by this Parameter

      • isImplicit

        public boolean isImplicit​()
        Returns true if this parameter is implicitly declared in source code; returns false otherwise.
        Returns:
        true if and only if this parameter is implicitly declared as defined by The Java™ Language Specification.

      • isSynthetic

        public boolean isSynthetic​()
        Returns true if this parameter is neither implicitly nor explicitly declared in source code; returns false otherwise.
        Returns:
        true if and only if this parameter is a synthetic construct as defined by The Java™ Language Specification.
        See The Java™ Language Specification:
        13.1 The Form of a Binary

      • isVarArgs

        public boolean isVarArgs​()
        Returns true if this parameter represents a variable argument list; returns false otherwise.
        Returns:
        true if an only if this parameter represents a variable argument list.

      • getAnnotation

        public <T extends Annotation> T getAnnotation​(Class<T> annotationClass)
        Returns this element's annotation for the specified type if such an annotation is present, else null.
        Specified by:
        getAnnotation in interface AnnotatedElement
        Type Parameters:
        T - the type of the annotation to query for and return if present
        Parameters:
        annotationClass - the Class object corresponding to the annotation type
        Returns:
        this element's annotation for the specified annotation type if present on this element, else null
        Throws:
        NullPointerException - if the given annotation class is null

      • getAnnotationsByType

        public <T extends Annotation> T[] getAnnotationsByType​(Class<T> annotationClass)
        Returns annotations that are associated with this element. If there are no annotations associated with this element, the return value is an array of length 0. The difference between this method and AnnotatedElement.getAnnotation(Class) is that this method detects if its argument is a repeatable annotation type (JLS 9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
        Specified by:
        getAnnotationsByType in interface AnnotatedElement
        Type Parameters:
        T - the type of the annotation to query for and return if present
        Parameters:
        annotationClass - the Class object corresponding to the annotation type
        Returns:
        all this element's annotations for the specified annotation type if associated with this element, else an array of length zero
        Throws:
        NullPointerException - if the given annotation class is null

      • getDeclaredAnnotations

        public Annotation[] getDeclaredAnnotations​()
        Returns annotations that are directly present on this element. This method ignores inherited annotations. If there are no annotations directly present on this element, the return value is an array of length 0. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
        Specified by:
        getDeclaredAnnotations in interface AnnotatedElement
        Returns:
        annotations directly present on this element

      • getDeclaredAnnotation

        public <T extends Annotation> T getDeclaredAnnotation​(Class<T> annotationClass)
        Description copied from interface: AnnotatedElement
        Returns this element's annotation for the specified type if such an annotation is directly present, else null. This method ignores inherited annotations. (Returns null if no annotations are directly present on this element.)
        Specified by:
        getDeclaredAnnotation in interface AnnotatedElement
        Type Parameters:
        T - the type of the annotation to query for and return if directly present
        Parameters:
        annotationClass - the Class object corresponding to the annotation type
        Returns:
        this element's annotation for the specified annotation type if directly present on this element, else null
        Throws:
        NullPointerException - if the given annotation class is null

      • getDeclaredAnnotationsByType

        public <T extends Annotation> T[] getDeclaredAnnotationsByType​(Class<T> annotationClass)
        Description copied from interface: AnnotatedElement
        Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present. This method ignores inherited annotations. If there are no specified annotations directly or indirectly present on this element, the return value is an array of length 0. The difference between this method and AnnotatedElement.getDeclaredAnnotation(Class) is that this method detects if its argument is a repeatable annotation type (JLS 9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation if one is present. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
        Specified by:
        getDeclaredAnnotationsByType in interface AnnotatedElement
        Type Parameters:
        T - the type of the annotation to query for and return if directly or indirectly present
        Parameters:
        annotationClass - the Class object corresponding to the annotation type
        Returns:
        all this element's annotations for the specified annotation type if directly or indirectly present on this element, else an array of length zero
        Throws:
        NullPointerException - if the given annotation class is null

      • getAnnotations

        public Annotation[] getAnnotations​()
        Returns annotations that are present on this element. If there are no annotations present on this element, the return value is an array of length 0. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
        Specified by:
        getAnnotations in interface AnnotatedElement
        Returns:
        annotations present on this element