Chapter 21

21. java.awt.event Reference

ActionEvent

Name

ActionEvent (New)

[Graphic: Figure from the text]

Description

Action events are fired off when the user performs an action on a component, such as pushing a button, double-clicking on a list item, or selecting a menu item. There is only one action event type, ACTION_PERFORMED.

Class Definition

public class java.awt.event.ActionEvent
   extends java.awt.AWTEvent {
  // Constants
  public final static int ACTION_FIRST;
  public final static int ACTION_LAST;
  public final static int ACTION_PERFORMED;
  public final static int ALT_MASK;
  public final static int CTRL_MASK;
  public final static int META_MASK;
  public final static int SHIFT_MASK;
  // Constructors
  public ActionEvent (Object source, int id, String command);
  public ActionEvent (Object source, int id, String command, int modifiers);
  // Instance Methods
  public String getActionCommand();
  public int getModifiers();
  public String paramString();
}

Constants

ACTION_FIRST

public final static int ACTION_FIRST

Specifies the beginning range of action event ID values.

ACTION_LAST

public final static int ACTION_LAST

Specifies the ending range of action event ID values.

ACTION_PERFORMED

public final static int ACTION_PERFORMED

The only action event type; it indicates that the user has performed an action.

ALT_MASK

public final static int ALT_MASK

A constant representing the ALT key. ORed with other masks to form modifiers setting of an AWTEvent.

CTRL_MASK

public final static int CTRL_MASK

A constant representing the Control key. ORed with other masks to form modifiers setting of an AWTEvent.

META_MASK

public final static int META_MASK

A constant representing the META key. ORed with other masks to form modifiers setting of an AWTEvent.

SHIFT_MASK

public final static int SHIFT_MASK

A constant representing the Shift key. ORed with other masks to form modifiers setting of an AWTEvent.

Constructors

ActionEvent

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

Parameters

source

The object that generated the event.

id

The type ID of the event.

command

The action command string.

Description

Constructs an ActionEvent with the given characteristics.

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

Parameters

source

The object that generated the event.

id

The type ID of the event.

command

The action command string.

modifiers

A combination of the key mask constants.

Description

Constructs an ActionEvent with the given characteristics.

Instance Methods

getActionCommand

public String getActionCommand()

Returns

The action command string for this ActionEvent.

Description

Generally the action command string is the label of the component that generated the event. Also, when localization is necessary, the action command string can provide a setting that does not get localized.

getModifiers

public int getModifiers()

Returns

A combination of the key mask constants.

Description

Returns the modifier keys that were held down when this action was performed. This enables you to perform special processing if, for example, the user holds down Shift while pushing a button.

paramString

public String paramString()

Returns

String with current settings of ActionEvent.

Overrides

AWTEvent.paramString()

Description

Helper method for toString() to generate string of current settings.