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 Detail


        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

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

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

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

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

      • 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 Detail

      • 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