Class EventType

java.lang.Object

jdk.jfr.EventType

public final class EventType
extends Object

Describes an event, its fields, settings and annotations.

The following example shows how the EventType class can be used to print metadata about an event.

for (EventType eventType : FlightRecorder.getFlightRecorder().getEventTypes()) {
    System.out.println("Event Type: " + eventType.getName());
    if (eventType.getLabel() != null) {
        System.out.println("Label: " + eventType.getLabel());
    }
    if (eventType.getDescription() != null) {
        System.out.println("Description: " + eventType.getDescription());
    }
    StringJoiner s = new StringJoiner(" / ");
    for (String category : eventType.getCategoryNames()) {
        s.add(category);
    }
    System.out.println("Category: " + s);
    System.out.println("Fields: " + eventType.getFields().size());
    System.out.println("Annotations: " + eventType.getAnnotationElements().size());
    System.out.println("Settings: " + eventType.getSettingDescriptors().size());
    System.out.println("Enabled: " + eventType.isEnabled());
    System.out.println();
}

Since:

9

Method Summary

Modifier and Type	Method	Description
<A extends Annotation> A	getAnnotation(Class<A> annotationClass)	Returns the first annotation for the specified type if an annotation element with the same name is directly present, otherwise null.
List<AnnotationElement>	getAnnotationElements()	Returns an immutable list of annotation elements for this event type.
List<String>	getCategoryNames()	Returns the list of human-readable names that make up the categories for this event type (for example, "Java Application", "Statistics").
String	getDescription()	Returns a short sentence that describes the event class.
static EventType	getEventType(Class<? extends Event> eventClass)	Returns the event type for an event class, or null if it doesn't exist.
ValueDescriptor	getField(String name)	Returns the field with the specified name, or null if it doesn't exist.
List<ValueDescriptor>	getFields()	Returns an immutable list of descriptors that describe the event fields of this event type.
long	getId()	Returns a unique ID for this event type in the Java Virtual Machine (JVM).
String	getLabel()	Returns a human-readable name (for example, "CPU Load").
String	getName()	Returns an identifier for the event (for example, "jdk.CPULoad").
List<SettingDescriptor>	getSettingDescriptors()	Returns an immutable list of the setting descriptors that describe the available event settings for this event type.
boolean	isEnabled()	Returns true if the event is enabled and at least one recording is running, false otherwise.

Methods declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Method Details

getFields

public List<ValueDescriptor> getFields()

Returns an immutable list of descriptors that describe the event fields of this event type.

Returns:

the list of field descriptors, not null

getField

public ValueDescriptor getField(String name)

Returns the field with the specified name, or null if it doesn't exist.

It's possible to index into a nested field by using "." (for instance "thread.group.parent.name").

Parameters:

name - of the field to get, not null

Returns:

a value descriptor that describes the field, or null if the field with the specified name doesn't exist

getName

public String getName()

Returns an identifier for the event (for example, "jdk.CPULoad").

The identifier is the fully qualified name of the event class, if not set using the Name annotation.

Returns:

the name, not null

See Also:

• Name

getLabel

public String getLabel()

Returns a human-readable name (for example, "CPU Load").

The label of an event class can be set with Label.

Returns:

the label, or null if a label is not set

See Also:

• Label

getId

public long getId()

Returns a unique ID for this event type in the Java Virtual Machine (JVM).

Returns:

the ID that is used in the JVM

getAnnotationElements

public List<AnnotationElement> getAnnotationElements()

Returns an immutable list of annotation elements for this event type.

Returns:

an immutable list of annotations or an empty list if no annotations exists, not null

isEnabled

public boolean isEnabled()

Returns true if the event is enabled and at least one recording is running, false otherwise.

By default, the event is enabled. The event can be enabled or disabled by setting the enabled setting to true or false, programmatically or by using a configuration file. The event can also be disabled by annotating event with the @Enabled(false) annotation.

Returns:

true if event is enabled, false otherwise

See Also:

• Enabled
• Recording.enable(Class)

getDescription

public String getDescription()

Returns a short sentence that describes the event class.

The description of an event class can be set with Description.

Returns:

the description, or null if no description exists

See Also:

• Description

getAnnotation

public <A extends Annotation> A getAnnotation(Class<A> annotationClass)

Returns the first annotation for the specified type if an annotation element with the same name is directly present, otherwise null.

Type Parameters:

A - the type of the annotation to query for and return if present

Parameters:

annotationClass - the Class object that corresponds to the annotation type, not null

Returns:

this element's annotation for the specified annotation type if directly present, else null

getEventType

public static EventType getEventType(Class<? extends Event> eventClass)

Returns the event type for an event class, or null if it doesn't exist.

Parameters:

eventClass - the event class, not null

Returns:

the event class, or null if class doesn't exist

Throws:

IllegalArgumentException - if eventClass is an abstract class

IllegalStateException - if the class is annotated with Registered(false), but not manually registered

getSettingDescriptors

public List<SettingDescriptor> getSettingDescriptors()

Returns an immutable list of the setting descriptors that describe the available event settings for this event type.

Returns:

the list of setting descriptors for this event type, not null

getCategoryNames

public List<String> getCategoryNames()

Returns the list of human-readable names that make up the categories for this event type (for example, "Java Application", "Statistics").

Returns:

an immutable list of category names, or a list with the name "Uncategorized" if no category is set

See Also:

• Category