Class AnnotationElement

java.lang.Object

jdk.jfr.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 Summary

Constructor	Description
`AnnotationElement(Class<? extends Annotation> annotationType)`	Creates an annotation element to use for dynamically defined events.
`AnnotationElement(Class<? extends Annotation> annotationType, Object value)`	Creates an annotation element to use for dynamically defined events.
`AnnotationElement(Class<? extends Annotation> annotationType, Map<String,Object> values)`	Creates an annotation element to use for dynamically defined events.

Method Summary

Modifier and Type	Method	Description
`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`.
`List<AnnotationElement>`	`getAnnotationElements()`	Returns an immutable list of annotation elements for this `AnnotationElement`.
`long`	`getTypeId()`	Returns the type ID for this `AnnotationElement`.
`String`	`getTypeName()`	Returns the fully qualified name of the annotation type that corresponds to this `AnnotationElement` (for example, `"jdk.jfr.Label"`).
`Object`	`getValue(String name)`	Returns a value for this `AnnotationElement`.
`List<ValueDescriptor>`	`getValueDescriptors()`	Returns an immutable list of descriptors that describes the annotation values for this `AnnotationElement`.
`List<Object>`	`getValues()`	Returns an immutable list of annotation values in an order that matches the value descriptors for this `AnnotationElement`.
`boolean`	`hasValue(String name)`	Returns `true` if an annotation value with the specified name exists in this `AnnotationElement`.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Modifier and Type	Method	Description
`protected Object`	`clone()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this object.
`final void`	`notify()`	Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()`	Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()`	Returns a string representation of the object.
`final void`	`wait()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`final void`	`wait(long timeoutMillis)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis, int nanos)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

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 Details

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 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

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