Package com.google.common.reflect

Class Parameter

  • All Implemented Interfaces:
    AnnotatedElement
    @Beta
public final class Parameter
extends Object
implements AnnotatedElement
    Represents a method or constructor parameter.

    Note: Since Java 8 introduced Parameter to represent method and constructor parameters, this class is no longer necessary. We intend to deprecate it in a future version.

    Since:
    14.0
    Author:
    Ben Yu

    • Method Detail

      • isAnnotationPresent

        public boolean isAnnotationPresent​(Class<? extends Annotation> annotationType)
        Description copied from interface: java.lang.reflect.AnnotatedElement
        Returns true if an annotation for the specified type is present on this element, else false. This method is designed primarily for convenient access to marker annotations.

        The truth value returned by this method is equivalent to: getAnnotation(annotationClass) != null

        The body of the default method is specified to be the code above.

        Specified by:
        isAnnotationPresent in interface AnnotatedElement
        Parameters:
        annotationType - the Class object corresponding to the annotation type
        Returns:
        true if an annotation for the specified annotation type is present on this element, else false

      • getAnnotation

        @CheckForNull
public <A extends Annotation> A getAnnotation​(Class<A> annotationType)
        Description copied from interface: java.lang.reflect.AnnotatedElement
        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:
        A - the type of the annotation to query for and return if present
        Parameters:
        annotationType - 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

      • getAnnotations

        public Annotation[] getAnnotations()
        Description copied from interface: java.lang.reflect.AnnotatedElement
        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

      • getAnnotationsByType

        public <A extends Annotation> A[] getAnnotationsByType​(Class<A> annotationType)
        Description copied from interface: java.lang.reflect.AnnotatedElement
        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:
        A - the type of the annotation to query for and return if present
        Parameters:
        annotationType - 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
        Since:
        18.0

      • getDeclaredAnnotations

        public Annotation[] getDeclaredAnnotations()
        Description copied from interface: java.lang.reflect.AnnotatedElement
        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
        Since:
        18.0

      • getDeclaredAnnotation

        @CheckForNull
public <A extends Annotation> A getDeclaredAnnotation​(Class<A> annotationType)
        Description copied from interface: java.lang.reflect.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:
        A - the type of the annotation to query for and return if directly present
        Parameters:
        annotationType - 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
        Since:
        18.0

      • getDeclaredAnnotationsByType

        public <A extends Annotation> A[] getDeclaredAnnotationsByType​(Class<A> annotationType)
        Description copied from interface: java.lang.reflect.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:
        A - the type of the annotation to query for and return if directly or indirectly present
        Parameters:
        annotationType - 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
        Since:
        18.0

      • equals

        public boolean equals​(@CheckForNull
                      Object obj)
        Description copied from class: java.lang.Object
        Indicates whether some other object is "equal to" this one.

        The equals method implements an equivalence relation on non-null object references:

        • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
        • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
        • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
        • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
        • For any non-null reference value x, x.equals(null) should return false.

        The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

        Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

        Overrides:
        equals in class Object
        Parameters:
        obj - the reference object with which to compare.
        Returns:
        true if this object is the same as the obj argument; false otherwise.
        See Also:
        Object.hashCode(), HashMap

      • hashCode

        public int hashCode()
        Description copied from class: java.lang.Object
        Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

        The general contract of hashCode is:

        • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
        • If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
        • It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

        As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (The hashCode may or may not be implemented as some function of an object's memory address at some point in time.)

        Overrides:
        hashCode in class Object
        Returns:
        a hash code value for this object.
        See Also:
        Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

      • toString

        public String toString()
        Description copied from class: java.lang.Object
        Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

        The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of: 

         getClass().getName() + '@' + Integer.toHexString(hashCode())
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.