GarbageCollectionNotificationInfo (Java SE 21 & JDK 21)
Description: declaration: module: jdk.management, package: com.sun.management, class: GarbageCollectionNotificationInfo
Keywords: com.sun.management.GarbageCollectionNotificationInfo class

Module jdk.management
Package com.sun.management

# Class GarbageCollectionNotificationInfo

java.lang.Object
com.sun.management.GarbageCollectionNotificationInfo

All Implemented Interfaces:
  `CompositeDataView`

public class GarbageCollectionNotificationInfo extends Object implements CompositeDataView
The information about a garbage collection

A garbage collection notification is emitted by `GarbageCollectorMXBean` when the Java virtual machine completes a garbage collection action The notification emitted will contain the garbage collection notification information about the status of the memory:

- The name of the garbage collector used to perform the collection.
- The action performed by the garbage collector.
- The cause of the garbage collection action.
- A `GcInfo` object containing some statistics about the GC cycle (start time, end time) and the memory usage before and after the GC cycle.

A `CompositeData` representing the `GarbageCollectionNotificationInfo` object is stored in the userdata of a notification. The `from` method is provided to convert from a `CompositeData` to a `GarbageCollectionNotificationInfo` object. For example:

>           Notification notif;

>           // receive the notification emitted by a GarbageCollectorMXBean and set to notif
>           ...

>           String notifType = notif.getType();
>           if (notifType.equals(GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION)) {
>               // retrieve the garbage collection notification information
>               CompositeData cd = (CompositeData) notif.getUserData();
>               GarbageCollectionNotificationInfo info = GarbageCollectionNotificationInfo.from(cd);
>               ....
>           }

The type of the notification emitted by a `GarbageCollectorMXBean` is:

- A garbage collection notification.
  Used by every notification emitted by the garbage collector, the details about the notification are provided in the action String

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final String`
  `GARBAGE_COLLECTION_NOTIFICATION`
  Notification type denoting that the Java virtual machine has completed a garbage collection cycle.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `GarbageCollectionNotificationInfo(String gcName, String gcAction, String gcCause, GcInfo gcInfo)`
  Constructs a `GarbageCollectionNotificationInfo` object.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static GarbageCollectionNotificationInfo`
  `from(CompositeData cd)`
  Returns a `GarbageCollectionNotificationInfo` object represented by the given `CompositeData`.
  `String`
  `getGcAction()`
  Returns the action performed by the garbage collector
  `String`
  `getGcCause()`
  Returns the cause of the garbage collection
  `GcInfo`
  `getGcInfo()`
  Returns the GC information related to the last garbage collection
  `String`
  `getGcName()`
  Returns the name of the garbage collector used to perform the collection
  `CompositeData`
  `toCompositeData(CompositeType ct)`
  Return a `CompositeData` corresponding to the values in this object.

  ### Methods declared in class java.lang.Object

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

- ## Field Details

  - ### GARBAGE_COLLECTION_NOTIFICATION

    public static final String GARBAGE_COLLECTION_NOTIFICATION
    Notification type denoting that the Java virtual machine has completed a garbage collection cycle. This notification is emitted by a `GarbageCollectorMXBean`. The value of this notification type is `com.sun.management.gc.notification`.
    See Also:
      - Constant Field Values

- ## Constructor Details

  - ### GarbageCollectionNotificationInfo

    public GarbageCollectionNotificationInfo(String gcName, String gcAction, String gcCause, GcInfo gcInfo)
    Constructs a `GarbageCollectionNotificationInfo` object.
    Parameters:
      `gcName` - The name of the garbage collector used to perform the collection
      `gcAction` - The name of the action performed by the garbage collector
      `gcCause` - The cause of the garbage collection action
      `gcInfo` - a GcInfo object providing statistics about the GC cycle

- ## Method Details

  - ### getGcName

    public String getGcName()
    Returns the name of the garbage collector used to perform the collection
    Returns:
      the name of the garbage collector used to perform the collection

  - ### getGcAction

    public String getGcAction()
    Returns the action performed by the garbage collector
    Returns:
      the action performed by the garbage collector

  - ### getGcCause

    public String getGcCause()
    Returns the cause of the garbage collection
    Returns:
      the cause of the garbage collection

  - ### getGcInfo

    public GcInfo getGcInfo()
    Returns the GC information related to the last garbage collection
    Returns:
      the GC information related to the last garbage collection

  - ### from

    public static GarbageCollectionNotificationInfo from(CompositeData cd)
    Returns a `GarbageCollectionNotificationInfo` object represented by the given `CompositeData`. The given `CompositeData` must contain the following attributes:

    > description
    > Attribute Name | Type
    > --- | ---
    > gcName | `java.lang.String`
    > gcAction | `java.lang.String`
    > gcCause | `java.lang.String`
    > gcInfo | `javax.management.openmbean.CompositeData`

    Parameters:
      `cd` - `CompositeData` representing a `GarbageCollectionNotificationInfo`
    Returns:
      a `GarbageCollectionNotificationInfo` object represented by `cd` if `cd` is not `null`; `null` otherwise.
    Throws:
      `IllegalArgumentException` - if `cd` does not represent a `GarbaageCollectionNotificationInfo` object.

  - ### toCompositeData

    public CompositeData toCompositeData(CompositeType ct)
    Description copied from interface: `CompositeDataView`

    Return a `CompositeData` corresponding to the values in this object. The returned value should usually be an instance of `CompositeDataSupport`, or a class that serializes as a `CompositeDataSupport` via a `writeReplace` method. Otherwise, a remote client that receives the object might not be able to reconstruct it.

    Specified by:
      `toCompositeData` in interface `CompositeDataView`
    Parameters:
      `ct` - The expected `CompositeType` of the returned value. If the returned value is `cd`, then `cd.getCompositeType().equals(ct)` should be true. Typically this will be because `cd` is a `CompositeDataSupport` constructed with `ct` as its `CompositeType`.
    Returns:
      the `CompositeData`.