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java.awt
Class AWTKeyStroke

java.lang.Object
  extended byjava.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, 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
Author:
Arnaud Weber, David Mendenhall
See Also:
getAWTKeyStroke(char), Serialized Form

Field Summary
private static Map cache
           
private static AWTKeyStroke cacheKey
           
private  char keyChar
           
private  int keyCode
           
private static Map modifierKeywords
           
private  int modifiers
           
private  boolean onKeyRelease
           
private static Class subclass
           
private static Map vkMap
          Maps from VK_XXX (as a String) to an Integer.
 
Constructor Summary
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
private static AWTKeyStroke allocateNewInstance(Class clazz)
           
private  void copy(AWTKeyStroke rhs)
           
 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, given a 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.
private static AWTKeyStroke getCachedStroke(char keyChar, int keyCode, int modifiers, boolean onKeyRelease)
           
 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.
private static int getVKValue(String key)
          Returns the integer constant for the KeyEvent.VK field named key.
 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.
private static int mapNewModifiers(int modifiers)
           
private static int mapOldModifiers(int modifiers)
           
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
 

Field Detail

cache

private static Map cache

cacheKey

private static AWTKeyStroke cacheKey

subclass

private static Class subclass

modifierKeywords

private static Map modifierKeywords

vkMap

private static Map vkMap
Maps from VK_XXX (as a String) to an Integer. This is done to avoid the overhead of the reflective call to find the constant.

keyChar

private char keyChar

keyCode

private int keyCode

modifiers

private int modifiers

onKeyRelease

private boolean onKeyRelease
Constructor Detail

AWTKeyStroke

protected AWTKeyStroke()
Constructs an AWTKeyStroke with default values. The default values used are:
PropertyDefault 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

copy

private void copy(AWTKeyStroke rhs)

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

allocateNewInstance

private static AWTKeyStroke allocateNewInstance(Class clazz)
                                         throws InstantiationException
Throws:
InstantiationException

getCachedStroke

private static AWTKeyStroke getCachedStroke(char keyChar,
                                            int keyCode,
                                            int modifiers,
                                            boolean onKeyRelease)

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, given a 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: The old modifiers 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:

The modifiers consist of any combination of: The old modifiers 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:

The modifiers consist of any combination of: The old modifiers 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 key char from a KeyTyped event, and the key code 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

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 | button1 | button2 | button3
    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

getVKValue

private static int getVKValue(String key)
Returns the integer constant for the KeyEvent.VK field named key. This will throw an IllegalArgumentException if key is not a valid constant.

getKeyChar

public final char getKeyChar()
Returns the character for this AWTKeyStroke.

Returns:
a char value
See Also:
getAWTKeyStroke(char)

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)

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), Hashtable

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(), Hashtable

toString

public String toString()
Returns a string that displays and identifies this object's properties.

Overrides:
toString in class Object
Returns:
a String representation of this object

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

mapOldModifiers

private static int mapOldModifiers(int modifiers)

mapNewModifiers

private static int mapNewModifiers(int modifiers)
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