public class

HierarchyEvent

extends AWTEvent
java.lang.Object
   ↳ java.util.EventObject
     ↳ java.awt.AWTEvent
       ↳ java.awt.event.HierarchyEvent

Class Overview

An event which indicates a change to the Component hierarchy to which a Component belongs.

  • Hierarchy Change Events (HierarchyListener)
    • addition of an ancestor
    • removal of an ancestor
    • hierarchy made displayable
    • hierarchy made undisplayable
    • hierarchy shown on the screen (both visible and displayable)
    • hierarchy hidden on the screen (either invisible or undisplayable)
  • Ancestor Reshape Events (HierarchyBoundsListener)
    • an ancestor was resized
    • an ancestor was moved

Hierarchy events are provided for notification purposes ONLY. The AWT will automatically handle changes to the hierarchy internally so that GUI layout and displayability works properly regardless of whether a program is receiving these events or not.

This event is generated by a Container object (such as a Panel) when the Container is added, removed, moved, or resized, and passed down the hierarchy. It is also generated by a Component object when that object's addNotify, removeNotify, show, or hide method is called. ANCESTOR_MOVED and ANCESTOR_RESIZED events are dispatched to every HierarchyBoundsListener or HierarchyBoundsAdapter object which registered to receive such events using the Component's addHierarchyBoundsListener method. (HierarchyBoundsAdapter objects implement the HierarchyBoundsListener interface.) HIERARCHY_CHANGED events are dispatched to every HierarchyListener object which registered to receive such events using the Component's addHierarchyListener method. Each such listener object gets this HierarchyEvent when the event occurs.

See Also

Summary

Constants
int ANCESTOR_MOVED The event id indicating an ancestor-Container was moved.
int ANCESTOR_RESIZED The event id indicating an ancestor-Container was resized.
int DISPLAYABILITY_CHANGED Indicates that the HIERARCHY_CHANGED event was generated due to a change in the displayability of the hierarchy.
int HIERARCHY_CHANGED The event id indicating that modification was made to the entire hierarchy tree.
int HIERARCHY_FIRST Marks the first integer id for the range of hierarchy event ids.
int HIERARCHY_LAST Marks the last integer id for the range of ancestor event ids.
int PARENT_CHANGED Indicates that the HIERARCHY_CHANGED event was generated by a reparenting operation.
int SHOWING_CHANGED Indicates that the HIERARCHY_CHANGED event was generated due to a change in the showing state of the hierarchy.
[Expand]
Inherited Constants
From class java.awt.AWTEvent
[Expand]
Inherited Fields
From class java.awt.AWTEvent
From class java.util.EventObject
Public Constructors
HierarchyEvent(Component source, int id, Component changed, Container changedParent)
Constructs an HierarchyEvent object to identify a change in the Component hierarchy.
HierarchyEvent(Component source, int id, Component changed, Container changedParent, long changeFlags)
Constructs an HierarchyEvent object to identify a change in the Component hierarchy.
Public Methods
long getChangeFlags()
Returns a bitmask which indicates the type(s) of HIERARCHY_CHANGED events represented in this event object.
Component getChanged()
Returns the Component at the top of the hierarchy which was changed.
Container getChangedParent()
Returns the parent of the Component returned by getChanged().
Component getComponent()
Returns the originator of the event.
String paramString()
Returns a parameter string identifying this event.
[Expand]
Inherited Methods
From class java.awt.AWTEvent
From class java.util.EventObject
From class java.lang.Object

Constants

public static final int ANCESTOR_MOVED

The event id indicating an ancestor-Container was moved.

Constant Value: 1401 (0x00000579)

public static final int ANCESTOR_RESIZED

The event id indicating an ancestor-Container was resized.

Constant Value: 1402 (0x0000057a)

public static final int DISPLAYABILITY_CHANGED

Indicates that the HIERARCHY_CHANGED event was generated due to a change in the displayability of the hierarchy. To discern the current displayability of the hierarchy, call Component.isDisplayable. Displayability changes occur in response to explicit or implicit calls to Component.addNotify and Component.removeNotify.

See Also
Constant Value: 2 (0x00000002)

public static final int HIERARCHY_CHANGED

The event id indicating that modification was made to the entire hierarchy tree.

Constant Value: 1400 (0x00000578)

public static final int HIERARCHY_FIRST

Marks the first integer id for the range of hierarchy event ids.

Constant Value: 1400 (0x00000578)

public static final int HIERARCHY_LAST

Marks the last integer id for the range of ancestor event ids.

Constant Value: 1402 (0x0000057a)

public static final int PARENT_CHANGED

Indicates that the HIERARCHY_CHANGED event was generated by a reparenting operation.

Constant Value: 1 (0x00000001)

public static final int SHOWING_CHANGED

Indicates that the HIERARCHY_CHANGED event was generated due to a change in the showing state of the hierarchy. To discern the current showing state of the hierarchy, call Component.isShowing. Showing state changes occur when either the displayability or visibility of the hierarchy occurs. Visibility changes occur in response to explicit or implicit calls to Component.show and Component.hide.

See Also
Constant Value: 4 (0x00000004)

Public Constructors

public HierarchyEvent (Component source, int id, Component changed, Container changedParent)

Constructs an HierarchyEvent object to identify a change in the Component hierarchy.

Note that passing in an invalid id results in unspecified behavior. This method throws an IllegalArgumentException if source is null.

Parameters
source the Component object that originated the event
id an integer indicating the type of event
changed the Component at the top of the hierarchy which was changed
changedParent the parent of changed; this may be the parent before or after the change, depending on the type of change
Throws
IllegalArgumentException if source is null

public HierarchyEvent (Component source, int id, Component changed, Container changedParent, long changeFlags)

Constructs an HierarchyEvent object to identify a change in the Component hierarchy.

Note that passing in an invalid id results in unspecified behavior. This method throws an IllegalArgumentException if source is null.

Parameters
source the Component object that originated the event
id an integer indicating the type of event
changed the Component at the top of the hierarchy which was changed
changedParent the parent of changed; this may be the parent before or after the change, depending on the type of change
changeFlags a bitmask which indicates the type(s) of HIERARCHY_CHANGED events represented in this event object
Throws
IllegalArgumentException if source is null

Public Methods

public long getChangeFlags ()

Returns a bitmask which indicates the type(s) of HIERARCHY_CHANGED events represented in this event object. The bits have been bitwise-ored together.

Returns
  • the bitmask, or 0 if this is not an HIERARCHY_CHANGED event

public Component getChanged ()

Returns the Component at the top of the hierarchy which was changed.

Returns
  • the changed Component

public Container getChangedParent ()

Returns the parent of the Component returned by getChanged(). For a HIERARCHY_CHANGED event where the change was of type PARENT_CHANGED via a call to Container.add, the parent returned is the parent after the add operation. For a HIERARCHY_CHANGED event where the change was of type PARENT_CHANGED via a call to Container.remove, the parent returned is the parent before the remove operation. For all other events and types, the parent returned is the parent during the operation.

Returns
  • the parent of the changed Component

public Component getComponent ()

Returns the originator of the event.

Returns
  • the Component object that originated the event, or null if the object is not a Component.

public String paramString ()

Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.

Returns
  • a string identifying the event and its attributes