java.awt.event
Class ActionEvent

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

public class ActionEvent

extends AWTEvent

A semantic event which indicates that a component-defined action occured. This high-level event is generated by a component (such as a Button) when the component-specific action occurs (such as being pressed). The event is passed to every every ActionListener object that registered to receive such events using the component's addActionListener method.

The object that implements the ActionListener interface gets this ActionEvent when the event occurs. The listener is therefore spared the details of processing individual mouse movements and mouse clicks, and can instead process a "meaningful" (semantic) event like "button pressed".

See Also:

ActionListener, Tutorial: Java 1.1 Event Model, Reference: The Java Class Libraries (update file), Serialized Form

Field Summary

static int	ACTION_FIRST The first number in the range of ids used for action events.
static int	ACTION_LAST The last number in the range of ids used for action events.
static int	ACTION_PERFORMED This event id indicates that a meaningful action occured.
static int	ALT_MASK The alt modifier.
static int	CTRL_MASK The control modifier.
static int	META_MASK The meta modifier.
static int	SHIFT_MASK The shift modifier.

Fields inherited from class java.awt.AWTEvent

ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK

Fields inherited from class java.util.EventObject

source

Constructor Summary

ActionEvent(Object source, int id, String command)
Constructs an ActionEvent object.

ActionEvent(Object source, int id, String command, int modifiers)
Constructs an ActionEvent object with modifier keys.

Method Summary

String	getActionCommand() Returns the command string associated with this action.
int	getModifiers() Returns the modifier keys held down during this action event.
String	paramString() Returns a parameter string identifying this action event.

Methods inherited from class java.awt.AWTEvent

consume, finalize, getID, isConsumed, toString

Methods inherited from class java.util.EventObject

getSource

Methods inherited from class java.lang.Object

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

Field Detail

SHIFT_MASK

public static final int SHIFT_MASK

The shift modifier. An indicator that the shift key was held down during the event.

CTRL_MASK

public static final int CTRL_MASK

The control modifier. An indicator that the control key was held down during the event.

META_MASK

public static final int META_MASK

The meta modifier. An indicator that the meta key was held down during the event.

ALT_MASK

public static final int ALT_MASK

The alt modifier. An indicator that the alt key was held down during the event.

ACTION_FIRST

public static final int ACTION_FIRST

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

ACTION_LAST

public static final int ACTION_LAST

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

ACTION_PERFORMED

public static final int ACTION_PERFORMED

This event id indicates that a meaningful action occured.

Constructor Detail

ActionEvent

public ActionEvent(Object source,
                   int id,
                   String command)

Constructs an ActionEvent object.

Parameters:

source - the object that originated the event

id - an integer that identifies the event

command - a string that may specify a command (possibly one of several) associated with the event

ActionEvent

public ActionEvent(Object source,
                   int id,
                   String command,
                   int modifiers)

Constructs an ActionEvent object with modifier keys.

Parameters:

source - the object that originated the event

id - an integer that identifies the event

command - a string that may specify a command (possibly one of several) associated with the event

modifiers - the modifier keys held down during this action

Method Detail

getActionCommand

public String getActionCommand()

Returns the command string associated with this action. This string allows a "modal" component to specify one of several commands, depending on its state. For example, a single button might toggle between "show details" and "hide details". The source object and the event would be the same in each case, but the command string would identify the intended action.

Returns:

the string identifying the command for this event

getModifiers

public int getModifiers()

Returns the modifier keys held down during this action event.

Returns:

the integer sum of the modifier constants

paramString

public String paramString()

Returns a parameter string identifying this action event. This method is useful for event-logging and for debugging.

Returns:

a string identifying the event and its associated command

Overrides:

paramString in class AWTEvent