java.awt

Class AWTKeyStroke

java.lang.Object

java.awt.AWTKeyStroke

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

KeyStroke

public class AWTKeyStroke
extends Object
implements Serializable

An AWTKeyStroke represents a key action on the keyboard, or equivalent input device. AWTKeyStrokes can correspond to only a press or release of a particular key, just as KEY_PRESSED and KEY_RELEASED KeyEvents do; alternately, they can correspond to typing a specific Java character, just as KEY_TYPED KeyEvents do. In all cases, AWTKeyStrokes can specify modifiers (alt, shift, control, meta, altGraph, or a combination thereof) which must be present during the action for an exact match.

AWTKeyStrokes are immutable, and are intended to be unique. Client code should never create an AWTKeyStroke on its own, but should instead use a variant of getAWTKeyStroke. Client use of these factory methods allows the AWTKeyStroke implementation to cache and share instances efficiently.

Since:

1.4

See Also:

getAWTKeyStroke(char), Serialized Form

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AWTKeyStroke() Constructs an AWTKeyStroke with default values.
protected	AWTKeyStroke(char keyChar, int keyCode, int modifiers, boolean onKeyRelease) Constructs an AWTKeyStroke with the specified values.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object anObject) Returns true if this object is identical to the specified object.
static AWTKeyStroke	getAWTKeyStroke(char keyChar) Returns a shared instance of an AWTKeyStroke that represents a KEY_TYPED event for the specified character.
static AWTKeyStroke	getAWTKeyStroke(Character keyChar, int modifiers) Returns a shared instance of an AWTKeyStroke that represents a KEY_TYPED event for the specified Character object and a set of modifiers.
static AWTKeyStroke	getAWTKeyStroke(int keyCode, int modifiers) Returns a shared instance of an AWTKeyStroke, given a numeric key code and a set of modifiers.
static AWTKeyStroke	getAWTKeyStroke(int keyCode, int modifiers, boolean onKeyRelease) Returns a shared instance of an AWTKeyStroke, given a numeric key code and a set of modifiers, specifying whether the key is activated when it is pressed or released.
static AWTKeyStroke	getAWTKeyStroke(String s) Parses a string and returns an AWTKeyStroke.
static AWTKeyStroke	getAWTKeyStrokeForEvent(KeyEvent anEvent) Returns an AWTKeyStroke which represents the stroke which generated a given KeyEvent.
char	getKeyChar() Returns the character for this AWTKeyStroke.
int	getKeyCode() Returns the numeric key code for this AWTKeyStroke.
int	getKeyEventType() Returns the type of KeyEvent which corresponds to this AWTKeyStroke.
int	getModifiers() Returns the modifier keys for this AWTKeyStroke.
int	hashCode() Returns a numeric value for this object that is likely to be unique, making it a good choice as the index value in a hash table.
boolean	isOnKeyRelease() Returns whether this AWTKeyStroke represents a key release.
protected Object	readResolve() Returns a cached instance of AWTKeyStroke (or a subclass of AWTKeyStroke) which is equal to this instance.
protected static void	registerSubclass(Class<?> subclass) Registers a new class which the factory methods in AWTKeyStroke will use when generating new instances of AWTKeyStrokes.
String	toString() Returns a string that displays and identifies this object's properties.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

AWTKeyStroke

protected AWTKeyStroke()

Constructs an AWTKeyStroke with default values. The default values used are:

Property	Default Value
Key Char	KeyEvent.CHAR_UNDEFINED
Key Code	KeyEvent.VK_UNDEFINED
Modifiers	none
On key release?	false

AWTKeyStrokes should not be constructed by client code. Use a variant of getAWTKeyStroke instead.

See Also:

getAWTKeyStroke(char)

AWTKeyStroke

protected AWTKeyStroke(char keyChar,
                       int keyCode,
                       int modifiers,
                       boolean onKeyRelease)

Constructs an AWTKeyStroke with the specified values. AWTKeyStrokes should not be constructed by client code. Use a variant of getAWTKeyStroke instead.

Parameters:

keyChar - the character value for a keyboard key

keyCode - the key code for this AWTKeyStroke

modifiers - a bitwise-ored combination of any modifiers

onKeyRelease - true if this AWTKeyStroke corresponds to a key release; false otherwise

See Also:

getAWTKeyStroke(char)

Method Detail

registerSubclass

protected static void registerSubclass(Class<?> subclass)

Registers a new class which the factory methods in AWTKeyStroke will use when generating new instances of AWTKeyStrokes. After invoking this method, the factory methods will return instances of the specified Class. The specified Class must be either AWTKeyStroke or derived from AWTKeyStroke, and it must have a no-arg constructor. The constructor can be of any accessibility, including private. This operation flushes the current AWTKeyStroke cache.

Parameters:

subclass - the new Class of which the factory methods should create instances

Throws:

IllegalArgumentException - if subclass is null, or if subclass does not have a no-arg constructor

ClassCastException - if subclass is not AWTKeyStroke, or a class derived from AWTKeyStroke

getAWTKeyStroke

public static AWTKeyStroke getAWTKeyStroke(char keyChar)

Returns a shared instance of an AWTKeyStroke that represents a KEY_TYPED event for the specified character.

Parameters:

keyChar - the character value for a keyboard key

Returns:

an AWTKeyStroke object for that key

getAWTKeyStroke

public static AWTKeyStroke getAWTKeyStroke(Character keyChar,
                                           int modifiers)

Returns a shared instance of an AWTKeyStroke that represents a KEY_TYPED event for the specified Character object and a set of modifiers. Note that the first parameter is of type Character rather than char. This is to avoid inadvertent clashes with calls to getAWTKeyStroke(int keyCode, int modifiers). The modifiers consist of any combination of following:

• java.awt.event.InputEvent.SHIFT_DOWN_MASK
• java.awt.event.InputEvent.CTRL_DOWN_MASK
• java.awt.event.InputEvent.META_DOWN_MASK
• java.awt.event.InputEvent.ALT_DOWN_MASK
• java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK

The old modifiers listed below also can be used, but they are mapped to _DOWN_ modifiers.

• java.awt.event.InputEvent.SHIFT_MASK
• java.awt.event.InputEvent.CTRL_MASK
• java.awt.event.InputEvent.META_MASK
• java.awt.event.InputEvent.ALT_MASK
• java.awt.event.InputEvent.ALT_GRAPH_MASK

also can be used, but they are mapped to _DOWN_ modifiers. Since these numbers are all different powers of two, any combination of them is an integer in which each bit represents a different modifier key. Use 0 to specify no modifiers.

Parameters:

keyChar - the Character object for a keyboard character

modifiers - a bitwise-ored combination of any modifiers

Returns:

an AWTKeyStroke object for that key

Throws:

IllegalArgumentException - if keyChar is null

See Also:

InputEvent

getAWTKeyStroke

public static AWTKeyStroke getAWTKeyStroke(int keyCode,
                                           int modifiers,
                                           boolean onKeyRelease)

Returns a shared instance of an AWTKeyStroke, given a numeric key code and a set of modifiers, specifying whether the key is activated when it is pressed or released.

The "virtual key" constants defined in java.awt.event.KeyEvent can be used to specify the key code. For example:

• java.awt.event.KeyEvent.VK_ENTER
• java.awt.event.KeyEvent.VK_TAB
• java.awt.event.KeyEvent.VK_SPACE

Alternatively, the key code may be obtained by calling java.awt.event.KeyEvent.getExtendedKeyCodeForChar. The modifiers consist of any combination of:

• java.awt.event.InputEvent.SHIFT_DOWN_MASK
• java.awt.event.InputEvent.CTRL_DOWN_MASK
• java.awt.event.InputEvent.META_DOWN_MASK
• java.awt.event.InputEvent.ALT_DOWN_MASK
• java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK

The old modifiers

• java.awt.event.InputEvent.SHIFT_MASK
• java.awt.event.InputEvent.CTRL_MASK
• java.awt.event.InputEvent.META_MASK
• java.awt.event.InputEvent.ALT_MASK
• java.awt.event.InputEvent.ALT_GRAPH_MASK

also can be used, but they are mapped to _DOWN_ modifiers. Since these numbers are all different powers of two, any combination of them is an integer in which each bit represents a different modifier key. Use 0 to specify no modifiers.

Parameters:

keyCode - an int specifying the numeric code for a keyboard key

modifiers - a bitwise-ored combination of any modifiers

onKeyRelease - true if the AWTKeyStroke should represent a key release; false otherwise

Returns:

an AWTKeyStroke object for that key

See Also:

KeyEvent, InputEvent

getAWTKeyStroke

public static AWTKeyStroke getAWTKeyStroke(int keyCode,
                                           int modifiers)

Returns a shared instance of an AWTKeyStroke, given a numeric key code and a set of modifiers. The returned AWTKeyStroke will correspond to a key press.

The "virtual key" constants defined in java.awt.event.KeyEvent can be used to specify the key code. For example:

• java.awt.event.KeyEvent.VK_ENTER
• java.awt.event.KeyEvent.VK_TAB
• java.awt.event.KeyEvent.VK_SPACE

The modifiers consist of any combination of:

• java.awt.event.InputEvent.SHIFT_DOWN_MASK
• java.awt.event.InputEvent.CTRL_DOWN_MASK
• java.awt.event.InputEvent.META_DOWN_MASK
• java.awt.event.InputEvent.ALT_DOWN_MASK
• java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK

The old modifiers

• java.awt.event.InputEvent.SHIFT_MASK
• java.awt.event.InputEvent.CTRL_MASK
• java.awt.event.InputEvent.META_MASK
• java.awt.event.InputEvent.ALT_MASK
• java.awt.event.InputEvent.ALT_GRAPH_MASK

also can be used, but they are mapped to _DOWN_ modifiers. Since these numbers are all different powers of two, any combination of them is an integer in which each bit represents a different modifier key. Use 0 to specify no modifiers.

Parameters:

keyCode - an int specifying the numeric code for a keyboard key

modifiers - a bitwise-ored combination of any modifiers

Returns:

an AWTKeyStroke object for that key

See Also:

KeyEvent, InputEvent

getAWTKeyStrokeForEvent

public static AWTKeyStroke getAWTKeyStrokeForEvent(KeyEvent anEvent)

Returns an AWTKeyStroke which represents the stroke which generated a given KeyEvent.

This method obtains the keyChar from a KeyTyped event, and the keyCode from a KeyPressed or KeyReleased event. The KeyEvent modifiers are obtained for all three types of KeyEvent.

Parameters:

anEvent - the KeyEvent from which to obtain the AWTKeyStroke

Returns:

the AWTKeyStroke that precipitated the event

Throws:

NullPointerException - if anEvent is null

getAWTKeyStroke

public static AWTKeyStroke getAWTKeyStroke(String s)

Parses a string and returns an AWTKeyStroke. The string must have the following syntax:

    <modifiers>* (<typedID> | <pressedReleasedID>)

    modifiers := shift | control | ctrl | meta | alt | altGraph
    typedID := typed <typedKey>
    typedKey := string of length 1 giving Unicode character.
    pressedReleasedID := (pressed | released) key
    key := KeyEvent key code name, i.e. the name following "VK_".
 

If typed, pressed or released is not specified, pressed is assumed. Here are some examples:

     "INSERT" => getAWTKeyStroke(KeyEvent.VK_INSERT, 0);
     "control DELETE" => getAWTKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);
     "alt shift X" => getAWTKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);
     "alt shift released X" => getAWTKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);
     "typed a" => getAWTKeyStroke('a');
 

Parameters:

s - a String formatted as described above

Returns:

an AWTKeyStroke object for that String

Throws:

IllegalArgumentException - if s is null, or is formatted incorrectly

getKeyChar

public final char getKeyChar()

Returns the character for this AWTKeyStroke.

Returns:

a char value

See Also:

getAWTKeyStroke(char), KeyEvent.getKeyChar()

getKeyCode

public final int getKeyCode()

Returns the numeric key code for this AWTKeyStroke.

Returns:

an int containing the key code value

See Also:

getAWTKeyStroke(int,int), KeyEvent.getKeyCode()

getModifiers

public final int getModifiers()

Returns the modifier keys for this AWTKeyStroke.

Returns:

an int containing the modifiers

See Also:

getAWTKeyStroke(int,int)

isOnKeyRelease

public final boolean isOnKeyRelease()

Returns whether this AWTKeyStroke represents a key release.

Returns:

true if this AWTKeyStroke represents a key release; false otherwise

See Also:

getAWTKeyStroke(int,int,boolean)

getKeyEventType

public final int getKeyEventType()

Returns the type of KeyEvent which corresponds to this AWTKeyStroke.

Returns:

KeyEvent.KEY_PRESSED, KeyEvent.KEY_TYPED, or KeyEvent.KEY_RELEASED

See Also:

KeyEvent

hashCode

public int hashCode()

Returns a numeric value for this object that is likely to be unique, making it a good choice as the index value in a hash table.

Overrides:

hashCode in class Object

Returns:

an int that represents this object

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

equals

public final boolean equals(Object anObject)

Returns true if this object is identical to the specified object.

Overrides:

equals in class Object

Parameters:

anObject - the Object to compare this object to

Returns:

true if the objects are identical

See Also:

Object.hashCode(), HashMap

toString

public String toString()

Returns a string that displays and identifies this object's properties. The String returned by this method can be passed as a parameter to getAWTKeyStroke(String) to produce a key stroke equal to this key stroke.

Overrides:

toString in class Object

Returns:

a String representation of this object

See Also:

getAWTKeyStroke(String)

readResolve

protected Object readResolve()
                      throws ObjectStreamException

Returns a cached instance of AWTKeyStroke (or a subclass of AWTKeyStroke) which is equal to this instance.

Returns:

a cached instance which is equal to this instance

Throws:

ObjectStreamException