The listener interface for receiving ancestor moved and resized events. The class that is interested in processing these events either implements this interface (and all the methods it contains) or extends the abstract HierarchyBoundsAdapter class (overriding only the method of interest). The listener object created from that class is then registered with a Component using the Component's addHierarchyBoundsListener method. When the hierarchy to which the Component belongs changes by the resizing or movement of an ancestor, the relevant method in the listener object is invoked, and the HierarchyEvent is passed to it.

Hierarchy events are provided for notification purposes ONLY; The AWT will automatically handle changes to the hierarchy internally so that GUI layout works properly regardless of whether a program registers an HierarchyBoundsListener or not.