Module jdk.jfr
Package jdk.jfr

Class AnnotationElement

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

    The following example shows how AnnotationElement can be used to dynamically define events. 

     
   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 use for dynamically defined events.

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

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

        To statically define events, see Event class.

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

      • AnnotationElement

        public AnnotationElement​(Class<? extends Annotation> annotationType,
                         Object value)
        Creates an annotation element to use for dynamically defined events.

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

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

        To statically define events, see Event class.

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

      • AnnotationElement

        public AnnotationElement​(Class<? extends Annotation> annotationType)
        Creates an annotation element to use for dynamically defined events.

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

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

        To statically define events, 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 that matches the value descriptors for this AnnotationElement.
        Returns:
        list of values, not null

      • getValueDescriptors

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

      • getAnnotationElements

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

      • getTypeName

        public String getTypeName()
        Returns the fully qualified name of the annotation type that corresponds to this AnnotationElement (for example, "jdk.jfr.Label").
        Returns:
        type name, not null

      • getValue

        public Object getValue​(String name)
        Returns a value for this AnnotationElement.
        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 specified name does not exist in the annotation

      • hasValue

        public boolean hasValue​(String name)
        Returns true if an annotation value with the specified name exists in this AnnotationElement.
        Parameters:
        name - name of the method in the annotation interface to find, 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 AnnotationElement with the same name exists, else null.
        Type Parameters:
        A - the type of the annotation to query for and return if it exists
        Parameters:
        annotationType - the Class object corresponding to the annotation type, not null
        Returns:
        this element's annotation for the specified annotation type if it it exists, else null

      • getTypeId

        public long getTypeId()
        Returns the type ID for this AnnotationElement.

        The ID is a unique identifier for the type in the Java Virtual Machine (JVM). The ID might not be the same between JVM instances.

        Returns:
        the type ID, not negative