HierarchyEvent
Class HierarchyEvent
- java.lang.Object
-
- java.util.EventObject
-
- java.awt.AWTEvent
-
- java.awt.event.HierarchyEvent
- All Implemented Interfaces:
- Serializable
public class HierarchyEvent extends AWTEvent
An event which indicates a change to the Component
hierarchy to which 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. The 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.) The 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.
An unspecified behavior will be caused if the id
parameter of any particular HierarchyEvent
instance is not in the range from HIERARCHY_FIRST
to HIERARCHY_LAST
.
The changeFlags
parameter of any HierarchyEvent
instance takes one of the following values:
-
HierarchyEvent.PARENT_CHANGED
-
HierarchyEvent.DISPLAYABILITY_CHANGED
-
HierarchyEvent.SHOWING_CHANGED
- Since:
- 1.3
- See Also:
-
HierarchyListener
,HierarchyBoundsAdapter
,HierarchyBoundsListener
, Serialized Form
Fields
HIERARCHY_FIRST
public static final int HIERARCHY_FIRST
Marks the first integer id for the range of hierarchy event ids.
HIERARCHY_CHANGED
public static final int HIERARCHY_CHANGED
The event id indicating that modification was made to the entire hierarchy tree.
ANCESTOR_MOVED
public static final int ANCESTOR_MOVED
The event id indicating an ancestor-Container was moved.
ANCESTOR_RESIZED
public static final int ANCESTOR_RESIZED
The event id indicating an ancestor-Container was resized.
HIERARCHY_LAST
public static final int HIERARCHY_LAST
Marks the last integer id for the range of ancestor event ids.
PARENT_CHANGED
public static final int PARENT_CHANGED
A change flag indicates that the HIERARCHY_CHANGED
event was generated by a reparenting operation.
DISPLAYABILITY_CHANGED
public static final int DISPLAYABILITY_CHANGED
A change flag indicates that the HIERARCHY_CHANGED
event was generated due to the changing of the hierarchy displayability. To discern the current displayability of the hierarchy, call the Component.isDisplayable
method. Displayability changes occur in response to explicit or implicit calls of the Component.addNotify
and Component.removeNotify
methods.
- See Also:
-
Component.isDisplayable()
,Component.addNotify()
,Component.removeNotify()
, Constant Field Values
SHOWING_CHANGED
public static final int SHOWING_CHANGED
A change flag indicates that the HIERARCHY_CHANGED
event was generated due to the changing of the hierarchy showing state. To discern the current showing state of the hierarchy, call the Component.isShowing
method. Showing state changes occur when either the displayability or visibility of the hierarchy occurs. Visibility changes occur in response to explicit or implicit calls of the Component.show
and Component.hide
methods.
- See Also:
-
Component.isShowing()
,Component.addNotify()
,Component.removeNotify()
,Component.show()
,Component.hide()
, Constant Field Values
Constructors
HierarchyEvent
public HierarchyEvent(Component source, int id, Component changed, Container changedParent)
Constructs an HierarchyEvent
object to identify a change in the Component
hierarchy.
This method throws an IllegalArgumentException
if source
is null
.
- Parameters:
-
source
- TheComponent
object that originated the event -
id
- An integer indicating the type of event. For information on allowable values, see the class description forHierarchyEvent
-
changed
- TheComponent
at the top of the hierarchy which was changed -
changedParent
- The parent of thechanged
component. This may be the parent before or after the change, depending on the type of change - Throws:
-
IllegalArgumentException
- ifsource
isnull
- See Also:
-
EventObject.getSource()
,AWTEvent.getID()
,getChanged()
,getChangedParent()
HierarchyEvent
public HierarchyEvent(Component source, int id, Component changed, Container changedParent, long changeFlags)
Constructs an HierarchyEvent
object to identify a change in the Component
hierarchy.
This method throws an IllegalArgumentException
if source
is null
.
- Parameters:
-
source
- TheComponent
object that originated the event -
id
- An integer indicating the type of event. For information on allowable values, see the class description forHierarchyEvent
-
changed
- TheComponent
at the top of the hierarchy which was changed -
changedParent
- The parent of thechanged
component. 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 theHIERARCHY_CHANGED
events represented in this event object. For information on allowable values, see the class description forHierarchyEvent
- Throws:
-
IllegalArgumentException
- ifsource
is null - See Also:
-
EventObject.getSource()
,AWTEvent.getID()
,getChanged()
,getChangedParent()
,getChangeFlags()
Methods
getComponent
public Component getComponent()
Returns the originator of the event.
- Returns:
- the
Component
object that originated the event, ornull
if the object is not aComponent
.
getChanged
public Component getChanged()
Returns the Component at the top of the hierarchy which was changed.
- Returns:
- the changed Component
getChangedParent
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
getChangeFlags
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
paramString
public String paramString()
Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.
- Overrides:
-
paramString
in classAWTEvent
- Returns:
- a string identifying the event and its attributes
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