HierarchyEventpublic class HierarchyEvent extends AWTEvent 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. |
| Fields Summary |
|---|
| public static final int | HIERARCHY_FIRSTMarks the first integer id for the range of hierarchy event ids. | | public static final int | HIERARCHY_CHANGEDThe event id indicating that modification was made to the
entire hierarchy tree. | | public static final int | ANCESTOR_MOVEDThe event id indicating an ancestor-Container was moved. | | public static final int | ANCESTOR_RESIZEDThe event id indicating an ancestor-Container was resized. | | public static final int | HIERARCHY_LASTMarks the last integer id for the range of ancestor event ids. | | public static final int | PARENT_CHANGEDIndicates that the HIERARCHY_CHANGED event
was generated by a reparenting operation. | | public static final int | DISPLAYABILITY_CHANGEDIndicates 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. | | public static final int | SHOWING_CHANGEDIndicates 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. | | Component | changed | | Container | changedParent | | long | changeFlags |
| Constructors Summary |
|---|
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.
super(source, id);
this.changed = changed;
this.changedParent = changedParent;
| 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.
super(source, id);
this.changed = changed;
this.changedParent = changedParent;
this.changeFlags = changeFlags;
|
| Methods Summary |
|---|
| 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.
return changeFlags;
| | public java.awt.Component | getChanged()Returns the Component at the top of the hierarchy which was
changed.
return changed;
| | public java.awt.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.
return changedParent;
| | public java.awt.Component | getComponent()Returns the originator of the event.
return (source instanceof Component) ? (Component)source : null;
| | public java.lang.String | paramString()Returns a parameter string identifying this event.
This method is useful for event-logging and for debugging.
String typeStr;
switch(id) {
case ANCESTOR_MOVED:
typeStr = "ANCESTOR_MOVED ("+changed+","+changedParent+")";
break;
case ANCESTOR_RESIZED:
typeStr = "ANCESTOR_RESIZED ("+changed+","+changedParent+")";
break;
case HIERARCHY_CHANGED: {
typeStr = "HIERARCHY_CHANGED (";
boolean first = true;
if ((changeFlags & PARENT_CHANGED) != 0) {
first = false;
typeStr += "PARENT_CHANGED";
}
if ((changeFlags & DISPLAYABILITY_CHANGED) != 0) {
if (first) {
first = false;
} else {
typeStr += ",";
}
typeStr += "DISPLAYABILITY_CHANGED";
}
if ((changeFlags & SHOWING_CHANGED) != 0) {
if (first) {
first = false;
} else {
typeStr += ",";
}
typeStr += "SHOWING_CHANGED";
}
if (!first) {
typeStr += ",";
}
typeStr += changed + "," + changedParent + ")";
break;
}
default:
typeStr = "unknown type";
}
return typeStr;
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