ComponentEvent (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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Java^TM 2 Platform
Std. Ed. v1.4.1

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java.awt.event
Class ComponentEvent

java.lang.Object
  |
  +--java.util.EventObject
        |
        +--java.awt.AWTEvent
              |
              +--java.awt.event.ComponentEvent

All Implemented Interfaces:: Serializable

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.

Since:: 1.1
See Also:: ComponentAdapter, ComponentListener, Tutorial: Writing a Component Listener, Reference: The Java Class Libraries (update file), Serialized Form

Field Summary

static int COMPONENT_FIRST
          The first number in the range of ids used for component events.

static int COMPONENT_HIDDEN
          This event indicates that the component was rendered invisible.

static int COMPONENT_LAST
          The last number in the range of ids used for component events.

static int COMPONENT_MOVED
          This event indicates that the component's position changed.

static int COMPONENT_RESIZED
          This event indicates that the component's size changed.

static int COMPONENT_SHOWN
          This event indicates that the component was made visible.

Fields inherited from class java.awt.AWTEvent

ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, HIERARCHY_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, INVOCATION_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, PAINT_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, WINDOW_STATE_EVENT_MASK

Fields inherited from class java.util.EventObject

source

Constructor Summary

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

Method Summary

Component getComponent()
          Returns the originator of the event.

String paramString()
          Returns a parameter string identifying this event.

Methods inherited from class java.awt.AWTEvent

consume, getID, isConsumed, setSource, toString

Methods inherited from class java.util.EventObject

getSource

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

COMPONENT_FIRST

public static final int COMPONENT_FIRST

The first number in the range of ids used for component events.

See Also:: Constant Field Values

COMPONENT_LAST

public static final int COMPONENT_LAST

The last number in the range of ids used for component events.

See Also:: Constant Field Values

COMPONENT_MOVED

public static final int COMPONENT_MOVED

This event indicates that the component's position changed.

See Also:: Constant Field Values

COMPONENT_RESIZED

public static final int COMPONENT_RESIZED

This event indicates that the component's size changed.

See Also:: Constant Field Values

COMPONENT_SHOWN

public static final int COMPONENT_SHOWN

This event indicates that the component was made visible.

See Also:: Constant Field Values

COMPONENT_HIDDEN

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.

Note that passing in an invalid id results in unspecified behavior.

Parameters:

source - the Component that originated the event

id - an integer indicating the type of event

Method Detail

getComponent

public Component getComponent()

Returns the originator of the event.

Returns:: 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.

Overrides:: paramString in class AWTEvent

Returns:: a string identifying the event and its attributes