Module java.desktop

Class ComponentEvent

All Implemented Interfaces:
Direct Known Subclasses:
ContainerEvent, FocusEvent, InputEvent, PaintEvent, WindowEvent

public class ComponentEvent extends AWTEvent
A low-level event which indicates that a component moved, changed size, or changed visibility (also, the root class for the other component-level events).

Component events are provided for notification purposes ONLY; The AWT will automatically handle component moves and resizes internally so that GUI layout works properly regardless of whether a program is receiving these events or not.

In addition to serving as the base class for other component-related events (InputEvent, FocusEvent, WindowEvent, ContainerEvent), this class defines the events that indicate changes in a component's size, position, or visibility.

This low-level event is generated by a component object (such as a List) when the component is moved, resized, rendered invisible, or made visible again. The event is passed to every ComponentListener or ComponentAdapter object which registered to receive such events using the component's addComponentListener method. (ComponentAdapter objects implement the ComponentListener interface.) Each such listener object gets this ComponentEvent when the event occurs.

An unspecified behavior will be caused if the id parameter of any particular ComponentEvent instance is not in the range from COMPONENT_FIRST to COMPONENT_LAST.

See Also:
ComponentAdapter, ComponentListener, Tutorial: Writing a Component Listener, Serialized Form
  • Field Details


      public static final int COMPONENT_FIRST
      The first number in the range of ids used for component events.
      See Also:
      Constant Field Values

      public static final int COMPONENT_LAST
      The last number in the range of ids used for component events.
      See Also:
      Constant Field Values

      @Native public static final int COMPONENT_MOVED
      This event indicates that the component's position changed.
      See Also:
      Constant Field Values

      @Native public static final int COMPONENT_RESIZED
      This event indicates that the component's size changed.
      See Also:
      Constant Field Values

      @Native public static final int COMPONENT_SHOWN
      This event indicates that the component was made visible.
      See Also:
      Constant Field Values

      @Native public static final int COMPONENT_HIDDEN
      This event indicates that the component was rendered invisible.
      See Also:
      Constant Field Values
  • Constructor Details

    • ComponentEvent

      public ComponentEvent(Component source, int id)
      Constructs a ComponentEvent object.

      This method throws an IllegalArgumentException if source is null.

      source - The Component that originated the event
      id - An integer indicating the type of event. For information on allowable values, see the class description for ComponentEvent
      IllegalArgumentException - if source is null
      See Also:
      getComponent(), AWTEvent.getID()
  • Method Details

    • getComponent

      public Component getComponent()
      Returns the originator of the event.
      the Component object that originated the event, or null if the object is not a Component.
    • paramString

      public String paramString()
      Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.
      paramString in class AWTEvent
      a string identifying the event and its attributes