[Chapter 21] java.awt.event Reference

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| Chapter 21 |

# 21. java.awt.event Reference

Contents:
ActionListener
AdjustmentEvent
AdjustmentListener
ComponentAdapter
ComponentEvent
ComponentListener
ContainerAdapter
ContainerEvent
ContainerListener
FocusAdapter
FocusEvent
FocusListener
InputEvent
ItemEvent
ItemListener
KeyAdapter
KeyEvent
KeyListener
MouseAdapter
MouseEvent
MouseListener
MouseMotionAdapter
MouseMotionListener
PaintEvent
TextEvent
TextListener
WindowAdapter
WindowEvent
WindowListener

# ActionEvent

## Name

ActionEvent

##

## 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.

## See Also

`ActionListener`, `AWTEvent`, `String`

WindowListener |  | ActionListener