[Chapter 19] Event

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| Chapter 19 java.awt Reference |

# Event

## Name

Event

##

## Description

The `Event` class represents events that happen within the Java environment in a platform independent way. Events typically represent user actions, like typing a key or clicking the mouse. Although this class has been updated for the 1.1 release, it is only used for the 1.0 event model. When using the 1.1 event model, all events are represented by subclasses of `java.awt.AWTEvent`.

## Class Definition

    public class java.awt.Event
        extends java.lang.Object
        implements java.io.Serializable {

      // Constants
      public static final int ACTION_EVENT;
      public static final int ALT_MASK;
      public static final int BACK_SPACE;
      public static final int CAPS_LOCK;
      public static final int CTRL_MASK;
      public static final int DELETE;
      public static final int DOWN;
      public static final int END;
      public static final int ENTER;
      public static final int ESCAPE;
      public static final int F1;
      public static final int F2;
      public static final int F3;
      public static final int F4;
      public static final int F5;
      public static final int F6;
      public static final int F7;
      public static final int F8;
      public static final int F9;
      public static final int F10;
      public static final int F11;
      public static final int F12;
      public static final int GOT_FOCUS;
      public static final int HOME;
      public static final int INSERT;
      public static final int KEY_ACTION;
      public static final int KEY_ACTION_RELEASE;
      public static final int KEY_PRESS;
      public static final int KEY_RELEASE;
      public static final int LEFT;
      public static final int LIST_DESELECT;
      public static final int LIST_SELECT;
      public static final int LOAD_FILE;
      public static final int LOST_FOCUS;
      public static final int META_MASK;
      public static final int MOUSE_DOWN;
      public static final int MOUSE_DRAG;
      public static final int MOUSE_ENTER;
      public static final int MOUSE_EXIT;
      public static final int MOUSE_MOVE;
      public static final int MOUSE_UP;
      public static final int NUM_LOCK;
      public static final int PAUSE;
      public static final int PGDN;
      public static final int PGUP;
      public static final int PRINT_SCREEN;
      public static final int RIGHT;
      public static final int SAVE_FILE;
      public static final int SCROLL_ABSOLUTE;
      public static final int SCROLL_BEGIN;
      public static final int SCROLL_END;
      public static final int SCROLL_LINE_DOWN;
      public static final int SCROLL_LINE_UP;
      public static final int SCROLL_LOCK;
      public static final int SCROLL_PAGE_DOWN;
      public static final int SCROLL_PAGE_UP;
      public static final int SHIFT_MASK;
      public static final int TAB;
      public static final int UP;
      public static final int WINDOW_DEICONIFY;
      public static final int WINDOW_DESTROY;
      public static final int WINDOW_EXPOSE;
      public static final int WINDOW_ICONIFY;
      public static final int WINDOW_MOVED;

      // Variables
      public Object arg;
      public int clickCount;
      public Event evt;
      public int id;
      public int key;
      public int modifiers;
      public Object target;
      public long when;
      public int x;
      public int y;

      // Constructors
      public Event (Object target, int id, Object arg);
      public Event (Object target, long when, int id, int x, int y,
          int key, int modifiers);
      public Event (Object target, long when, int id, int x, int y,
          int key, int modifiers, Object arg);

      // Instance Methods
      public boolean controlDown();
      public boolean metaDown();
      public boolean shiftDown();
      public String toString();
      public void translate (int x, int y);

      // Protected Instance Methods
      protected String paramString();
    }

## Constants

### ACTION_EVENT

#### public static final int ACTION_EVENT

ID constant for Action `Event`.

### ALT_MASK

#### public static final int ALT_MASK

Mask for ALT key.

### BACK_SPACE

#### public static final int BACK_SPACE

ID constant for Backspace.

### CAPS_LOCK

#### public static final int CAPS_LOCK

ID constant for Caps Lock key.

### CTRL_MASK

#### public static final int CTRL_MASK

Mask for Control key.

### DELETE

#### public static final int DELETE

ID constant for Delete.

### DOWN

#### public static final int DOWN

ID constant for the down arrow key.

### END

#### public static final int END

ID constant for End key.

### ENTER

#### public static final int ENTER

ID constant for Enter key.

### ESCAPE

#### public static final int ESCAPE

ID constant for Escape key.

### F1

#### public static final int F1

ID constant for F1 key.

### F2

#### public static final int F2

ID constant for F2 key.

### F3

#### public static final int F3

ID constant for F3 key.

### F4

#### public static final int F4

ID constant for F4 key.

### F5

#### public static final int F5

ID constant for F5 key.

### F6

#### public static final int F6

ID constant for F6 key.

### F7

#### public static final int F7

ID constant for F7 key.

### F8

#### public static final int F8

ID constant for F8 key.

### F9

#### public static final int F9

ID constant for F9 key.

### F10

#### public static final int F10

ID constant for F10 key.

### F11

#### public static final int F11

ID constant for F11 key.

### F12

#### public static final int F12

ID constant for F12 key.

### GOT_FOCUS

#### public static final int GOT_FOCUS

ID constant for getting input focus `Event`.

### HOME

#### public static final int HOME

ID constant for Home key.

### INSERT

#### public static final int INSERT

ID constant for Insert key.

### KEY_ACTION

#### public static final int KEY_ACTION

ID constant for Special Key Down Event.

### KEY_ACTION_RELEASE

#### public static final int KEY_ACTION_RELEASE

ID constant for Special Key Up Event.

### KEY_PRESS

#### public static final int KEY_PRESS

ID constant for Key Down `Event`.

### KEY_RELEASE

#### public static final int KEY_RELEASE

ID constant for Key Up `Event`.

### LEFT

#### public static final int LEFT

ID constant for the left arrow key.

### LIST_DESELECT

#### public static final int LIST_DESELECT

ID constant for List DeSelect `Event`.

### LIST_SELECT

#### public static final int LIST_SELECT

ID constant for List Select `Event`.

### LOAD_FILE

#### public static final int LOAD_FILE

ID constant for File Load `Event`.

### LOST_FOCUS

#### public static final int LOST_FOCUS

ID constant for losing input focus `Event`.

### META_MASK

#### public static final int META_MASK

Mask for ALT key.

### MOUSE_DOWN

#### public static final int MOUSE_DOWN

ID constant for Mouse Down `Event`.

### MOUSE_DRAG

#### public static final int MOUSE_DRAG

ID constant for Mouse Drag `Event`.

### MOUSE_ENTER

#### public static final int MOUSE_ENTER

ID constant for Mouse Enter `Event`.

### MOUSE_EXIT

#### public static final int MOUSE_EXIT

ID constant for Mouse Exit `Event`.

### MOUSE_MOVE

#### public static final int MOUSE_MOVE

ID constant for Mouse Move `Event`.

### MOUSE_UP

#### public static final int MOUSE_UP

ID constant for Mouse Up `Event`.

### NUM_LOCK

#### public static final int NUM_LOCK

ID constant for Num Lock key.

### PAUSE

#### public static final int PAUSE

ID constant for Pause key.

### PGDN

#### public static final int PGDN

ID constant for PageDown key.

### PGUP

#### public static final int PGUP

ID constant for PageUp key.

### PRINT_SCREEN

#### public static final int PRINT_SCREEN

ID constant for Print Screen key.

### RIGHT

#### public static final int RIGHT

ID constant for the right arrow key.

### SAVE_FILE

#### public static final int SAVE_FILE

ID constant for File Save `Event`.

### SCROLL_ABSOLUTE

#### public static final int SCROLL_ABSOLUTE

ID constant for Absolute Scroll `Event`.

### SCROLL_BEGIN

#### public static final int SCROLL_ BEGIN

ID constant for Begin Scroll `Event`.

### SCROLL_END

#### public static final int SCROLL_ END

ID constant for End Scroll `Event`.

### SCROLL_LINE_DOWN

#### public static final int SCROLL_LINE_DOWN

ID constant for Line Down Scroll `Event`.

### SCROLL_LINE_UP

#### public static final int SCROLL_LINE_UP

ID constant for Line Up Scroll `Event`.

### SCROLL_LOCK

#### public static final int SCROLL_LOCK

Mask for Scroll Lock key.

### SCROLL_PAGE_DOWN

#### public static final int SCROLL_PAGE_DOWN

ID constant for Page Down Scroll `Event`.

### SCROLL_PAGE_UP

#### public static final int SCROLL_PAGE_UP

ID constant for Page Up Scroll `Event`.

### SHIFT_MASK

#### public static final int SHIFT_MASK

Mask for SHIFT key.

### TAB

#### public static final int TAB

ID constant for Tab key.

### UP

#### public static final int UP

ID constant for the up arrow key.

### WINDOW_DEICONIFY

#### public static final int WINDOW_DEICONIFY

ID constant for Window DeIconify `Event`.

### WINDOW_DESTROY

#### public static final int WINDOW_DESTROY

ID constant for Window Destroy `Event`.

### WINDOW_EXPOSE

#### public static final int WINDOW_EXPOSE

ID constant for Window Expose `Event`.

### WINDOW_ICONIFY

#### public static final int WINDOW_ICONIFY

ID constant for Window Iconify `Event`.

### WINDOW_MOVED

#### public static final int WINDOW_MOVED

ID constant for Window Move `Event`.

## Variables

### arg

#### public Object arg

A variable argument that is specific to the event type.

### clickCount

#### public int clickCount

The number of consecutive MOUSE_DOWN events.

### evt

#### public Event evt

A means of passing a linked list of events as one.

### id

#### public int id

The ID constant that identifies the `Event` type.

### key

#### public int key

Integer value of key pressed, or ID constant identifying a special key.

### modifiers

#### public int modifiers

The state of the shift/alt/control/meta keys, formed by ORing the masks for the appropriate keys.

### target

#### public Object target

The `Object` that generated the event.

### when

#### public long when

The time the event happened.

### x

#### public int x

The x position at which the event happened.

### y

#### public int y

The y position at which the event happened.

## Constructors

### Event

#### public Event (Object target, int id, Object arg)

Parameters

  target

    The component to which the `Event` should be delivered

  id

    The identifier of `Event`

  arg

    The `Object` that is the cause of the event

Description

  Constructs an `Event` object with the given values.

#### public Event (Object target, long when, int id, int x, int y, int key, int modifiers)

Parameters

  target

    The component to which the `Event` should be delivered

  when

    The time the event happened

  id

    The identifier of `Event`

  x

    The x position at which the event happened

  y

    The y position at which the event happened

  key

    Integer value of key pressed, or a constant identifying a special key

  modifiers

    The state of the shift/alt/control/meta keys

Description

  Constructs an `Event` object with the given values.

#### public Event (Object target, long when, int id, int x, int y, int key, int modifiers, Object arg)

Parameters

  target

    The component to which the `Event` should be delivered

  when

    The time the event happened

  id

    The identifier of `Event`

  x

    The x position at which the event happened

  y

    The y position at which the event happened

  key

    Integer value of key pressed, or a constant identifying a special key

  modifiers

    The state of the shift/alt/control/meta keys

  arg

    The `Object` that is the cause of the event

Description

  Constructs an `Event` object with the given values.

## Instance Methods

### controlDown

#### public boolean controlDown()

Returns

  `true` if the control key was down when the event was triggered, `false` otherwise.

Description

  Checks current settings for modifiers of the `Event`.

### metaDown

#### public boolean metaDown()

Returns

  `true` if the meta key was down when the event was triggered, `false` otherwise.

Description

  Checks current settings for modifiers of the `Event`.

### shiftDown

#### public boolean shiftDown()

Returns

  `true` if the shift key was down when the event was triggered, `false` otherwise.

Description

  Checks current settings for modifiers of the `Event`.

### toString

#### public String toString()

Returns

  A string representation of the `Event` object.

Overrides

  `Object.toString()`

### translate

#### public void translate (int x, int y)

Parameters

  x

    Amount to move `Event` in horizontal direction.

  y

    Amount to move `Event` in vertical direction.

Description

  Translates x and y coordinates of `Event` instance by `x` and `y`.

## Protected Instance Methods

### paramString

#### protected String paramString()

Returns

  String with current settings of `Event`.

Description

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

## See Also

`AWTEvent`, `Component`, `Object`, `String`

Dimension |  | EventQueue