Component
* hierarchy to which Component belongs.
* * 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 {@code ANCESTOR_MOVED} and
* {@code 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 {@code 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 {@code id} parameter
* of any particular {@code HierarchyEvent} instance is not
* in the range from {@code HIERARCHY_FIRST} to {@code HIERARCHY_LAST}.
*
* The {@code changeFlags} parameter of any {@code HierarchyEvent} instance takes one of the following
* values:
*
HIERARCHY_CHANGED event
* was generated by a reparenting operation.
*/
public static final int PARENT_CHANGED = 0x1;
/**
* 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 java.awt.Component#isDisplayable()
* @see java.awt.Component#addNotify()
* @see java.awt.Component#removeNotify()
*/
public static final int DISPLAYABILITY_CHANGED = 0x2;
/**
* 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 java.awt.Component#isShowing()
* @see java.awt.Component#addNotify()
* @see java.awt.Component#removeNotify()
* @see java.awt.Component#show()
* @see java.awt.Component#hide()
*/
public static final int SHOWING_CHANGED = 0x4;
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.
*
* @param source The Component object that
* originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link HierarchyEvent}
* @param changed The Component at the top of
* the hierarchy which was changed
* @param changedParent The parent of the changed component.
* This
* may be the parent before or after the
* change, depending on the type of change
* @throws IllegalArgumentException if source is {@code null}
* @see #getSource()
* @see #getID()
* @see #getChanged()
* @see #getChangedParent()
*/
public HierarchyEvent(Component source, int id, Component changed,
Container changedParent) {
super(source, id);
this.changed = changed;
this.changedParent = changedParent;
}
/**
* Constructs an HierarchyEvent object to identify
* a change in the Component hierarchy.
*
This method throws an
* IllegalArgumentException if source
* is null.
*
* @param source The Component object that
* originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link HierarchyEvent}
* @param changed The Component at the top
* of the hierarchy which was changed
* @param changedParent The parent of the changed component.
* This
* may be the parent before or after the
* change, depending on the type of change
* @param changeFlags A bitmask which indicates the type(s) of
* the HIERARCHY_CHANGED events
* represented in this event object.
* For information on allowable values, see
* the class description for {@link HierarchyEvent}
* @throws IllegalArgumentException if source is null
* @see #getSource()
* @see #getID()
* @see #getChanged()
* @see #getChangedParent()
* @see #getChangeFlags()
*/
public HierarchyEvent(Component source, int id, Component changed,
Container changedParent, long changeFlags) {
super(source, id);
this.changed = changed;
this.changedParent = changedParent;
this.changeFlags = changeFlags;
}
/**
* Returns the originator of the event.
*
* @return the Component object that originated
* the event, or null if the object is not a
* Component.
*/
public Component getComponent() {
return (source instanceof Component) ? (Component)source : null;
}
/**
* Returns the Component at the top of the hierarchy which was
* changed.
*
* @return the changed Component
*/
public Component getChanged() {
return changed;
}
/**
* 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 the parent of the changed Component
*/
public Container getChangedParent() {
return changedParent;
}
/**
* 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 the bitmask, or 0 if this is not an HIERARCHY_CHANGED
* event
*/
public long getChangeFlags() {
return changeFlags;
}
/**
* Returns a parameter string identifying this event.
* This method is useful for event-logging and for debugging.
*
* @return a string identifying the event and its attributes
*/
public String paramString() {
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;
}
}