HierarchyListener (Java SE 21 & JDK 21)
Description: declaration: module: java.desktop, package: java.awt.event, interface: HierarchyListener
Keywords: java.awt.event.HierarchyListener interface

Module java.desktop
Package java.awt.event

# Interface HierarchyListener

All Superinterfaces:
  `EventListener`

All Known Implementing Classes:
  `AWTEventMulticaster`

public interface HierarchyListener extends EventListener
The listener interface for receiving hierarchy changed events. The class that is interested in processing a hierarchy changed event should implement this interface. The listener object created from that class is then registered with a Component using the Component's `addHierarchyListener` method. When the hierarchy to which the Component belongs changes, the `hierarchyChanged` 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, displayability, and visibility work properly regardless of whether a program registers a `HierarchyListener` or not.

Since:
  1.3
See Also:
  - `HierarchyEvent`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `hierarchyChanged(HierarchyEvent e)`
  Called when the hierarchy has been changed.

- ## Method Details

  - ### hierarchyChanged

    void hierarchyChanged(HierarchyEvent e)
    Called when the hierarchy has been changed. To discern the actual type of change, call `HierarchyEvent.getChangeFlags()`.
    Parameters:
      `e` - the event to be processed
    See Also:
      - `HierarchyEvent.getChangeFlags()`