Module jdk.jfr
Package jdk.jfr

Class AnnotationElement


  • public final class AnnotationElement
extends Object
    Describes event metadata, such as labels, descriptions and units.

    An AnnotationElement carries metadata of already defined events, but can also be used to define events dynamically, like this. 

     
   List<AnnotationElement> typeAnnotations = new ArrayList<>();
   typeannotations.add(new AnnotationElement(Name.class, "com.example.HelloWorld");
   typeAnnotations.add(new AnnotationElement(Label.class, "Hello World"));
   typeAnnotations.add(new AnnotationElement(Description.class, "Helps programmer getting started"));

   List<AnnotationElement> fieldAnnotations = new ArrayList<>();
   fieldAnnotations.add(new AnnotationElement(Label.class, "Message"));

   List<ValueDescriptor> fields = new ArrayList<>();
   fields.add(new ValueDescriptor(String.class, "message", fieldAnnotations));

   EventFactory f = EventFactory.create(typeAnnotations, fields);
   Event event = f.newEvent();
   event.commit();

    Since:
    9

    • Constructor Detail

      • AnnotationElement

        public AnnotationElement​(Class<? extends Annotation> annotationType,
                         Map<String,Object> values)
        Creates an annotation element to be used when defining events dynamically.

        Supported value types are byte, int, short, long, double, float, boolean, char and String. Enums, arrays and classes are not supported.

        If annotationType carries annotations (directly present, indirectly present or associated), those will be recursively included. However, both the annotationType and any annotation found recursively must have the MetadataDefinition annotation.

        To define events statically, see Event class.

        Parameters:
        annotationType - interface extending java.lang.annotation.Annotation, not null
        values - a map with keys matching the method names of the specified annotation interface
        Throws:
        IllegalArgumentException - if value/key is null, an unsupported value type is used or a value/key that doesn't match the signatures in the annotation type

      • AnnotationElement

        public AnnotationElement​(Class<? extends Annotation> annotationType,
                         Object value)
        Creates an annotation element to be used when defining events dynamically.

        Supported value types are byte, int, short, long, double, float, boolean, char and String. Enums, arrays and classes are not supported.

        If annotationType carries annotations (directly present, indirectly present or associated), those will be recursively included. However, both the annotationType and any annotation found recursively must have the MetadataDefinition annotation.

        To define events statically, see Event class.

        Parameters:
        annotationType - interface extending java.lang.annotation.Annotation, not null
        value - the value that should match the value method of the specified annotationType
        Throws:
        IllegalArgumentException - if value/key is null, an unsupported value type is used or a value/key that doesn't match the signatures in the annotation type

      • AnnotationElement

        public AnnotationElement​(Class<? extends Annotation> annotationType)
        Creates an annotation element to be used when defining events dynamically.

        Supported value types are byte, short, int, long, double, float, boolean, char and String. Enums, arrays and classes are not supported.

        If annotationType carries annotations (directly present, indirectly present or associated), those will be recursively included. However, both the annotationType and any annotation found recursively must have the MetadataDefinition annotation.

        To define events statically, see Event class.

        Parameters:
        annotationType - interface extending java.lang.annotation.Annotation, not null

    • Method Detail

      • getValues

        public List<Object> getValues​()
        Returns an immutable list of annotation values in an order matching the value descriptors for this AnnotationElement.
        Returns:
        list of values, not null

      • getValueDescriptors

        public List<ValueDescriptor> getValueDescriptors​()
        Returns an immutable list of descriptors describing annotation values for this AnnotationElement.
        Returns:
        the list of value descriptor for this Annotation, not null

      • getAnnotationElements

        public List<AnnotationElement> getAnnotationElements​()
        Returns an immutable list of annotation elements for this annotation element.
        Returns:
        a list of meta annotation, not null

      • getTypeName

        public String getTypeName​()
        Returns the fully qualified name of the annotation type corresponding to this annotation element.
        Returns:
        type name, not null

      • getValue

        public Object getValue​(String name)
        Returns a value for this annotation element.
        Parameters:
        name - the name of the method in the annotation interface, not null.
        Returns:
        the annotation value, not null.
        Throws:
        IllegalArgumentException - if a method with the name could not be located in the annotation

      • hasValue

        public boolean hasValue​(String name)
        Returns true if an annotation value with the specified name exists in this annotation element.
        Parameters:
        name - name of the method in the annotation interface to check for, not null
        Returns:
        true if method exists, false otherwise

      • getAnnotation

        public final <A> A getAnnotation​(Class<? extends Annotation> annotationType)
        Returns the first annotation for the specified type if an annotation element with the same name is available, else null.
        Type Parameters:
        A - the type of the annotation to query for and return if available
        Parameters:
        annotationType - the Class object corresponding to the annotation type, not null
        Returns:
        this element's annotation for the specified annotation type if available, else null

      • getTypeId

        public long getTypeId​()
        Returns the type id for this annotation element.

        The type id is a unique identifier for the type in the JVM. It's not guaranteed to be the same between JVM instances.

        Returns:
        the type id, not negative