Module java.base
Package java.lang.reflect

Class Parameter

java.lang.Object
java.lang.reflect.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

    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.

    Methods declared in class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods declared in interface java.lang.reflect.AnnotatedElement

    isAnnotationPresent

  • Method Details

    • 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

    • hashCode

      public int hashCode()
      Returns a hash code based on the executable's hash code and the index.
      Overrides:
      hashCode in class Object
      Returns:
      A hash code based on the executable's hash code.
      See Also:
      Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

    • 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 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.

      Note that any annotation returned by this method is a declaration annotation.

      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.

      Note that any annotations returned by this method are declaration annotations.

      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.

      Note that any annotations returned by this method are declaration annotations.

      Specified by:
      getDeclaredAnnotations in interface AnnotatedElement
      Returns:
      annotations directly present on this element

    • getDeclaredAnnotation

      public <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. This method ignores inherited annotations. (Returns null if no annotations are directly present on this element.)

      Note that any annotation returned by this method is a declaration annotation.

      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)
      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.

      Note that any annotations returned by this method are declaration annotations.

      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.

      Note that any annotations returned by this method are declaration annotations.

      Specified by:
      getAnnotations in interface AnnotatedElement
      Returns:
      annotations present on this element