Class KeyStroke

java.lang.Object
java.awt.AWTKeyStroke
javax.swing.KeyStroke
All Implemented Interfaces:
Serializable
public class KeyStroke extends AWTKeyStroke
A KeyStroke represents a key action on the keyboard, or equivalent input device. KeyStrokes 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, KeyStrokes can specify modifiers (alt, shift, control, meta, altGraph, or a combination thereof) which must be present during the action for an exact match.

KeyStrokes are used to define high-level (semantic) action events. Instead of trapping every keystroke and throwing away the ones you are not interested in, those keystrokes you care about automatically initiate actions on the Components with which they are registered.

KeyStrokes are immutable, and are intended to be unique. Client code cannot create a KeyStroke; a variant of getKeyStroke must be used instead. These factory methods allow the KeyStroke implementation to cache and share instances efficiently.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans has been added to the java.beans package. Please see XMLEncoder.

Since:
1.2
See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    static KeyStroke
    getKeyStroke(char keyChar)
    Returns a shared instance of a KeyStroke that represents a KEY_TYPED event for the specified character.
    static KeyStroke
    getKeyStroke(char keyChar, boolean onKeyRelease)
    Deprecated.
    use getKeyStroke(char)
    static KeyStroke
    getKeyStroke(int keyCode, int modifiers)
    Returns a shared instance of a KeyStroke, given a numeric key code and a set of modifiers.
    static KeyStroke
    getKeyStroke(int keyCode, int modifiers, boolean onKeyRelease)
    Returns a shared instance of a KeyStroke, given a numeric key code and a set of modifiers, specifying whether the key is activated when it is pressed or released.
    static KeyStroke
    getKeyStroke(Character keyChar, int modifiers)
    Returns a shared instance of a KeyStroke that represents a KEY_TYPED event for the specified Character object and a set of modifiers.
    static KeyStroke
    getKeyStroke(String s)
    Parses a string and returns a KeyStroke.
    static KeyStroke
    getKeyStrokeForEvent(KeyEvent anEvent)
    Returns a KeyStroke which represents the stroke which generated a given KeyEvent.

    Methods declared in class AWTKeyStroke

    equals, getAWTKeyStroke, getAWTKeyStroke, getAWTKeyStroke, getAWTKeyStroke, getAWTKeyStroke, getAWTKeyStrokeForEvent, getKeyChar, getKeyCode, getKeyEventType, getModifiers, hashCode, isOnKeyRelease, readResolve, registerSubclass, toString
    Modifier and Type
    Method
    Description
    final 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(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(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(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.
    final char
    getKeyChar()
    Returns the character for this AWTKeyStroke.
    final int
    getKeyCode()
    Returns the numeric key code for this AWTKeyStroke.
    final int
    getKeyEventType()
    Returns the type of KeyEvent which corresponds to this AWTKeyStroke.
    final 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.
    final 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)
    Deprecated. 
    String
    toString()
    Returns a string that displays and identifies this object's properties.

    Methods declared in class Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Creates and returns a copy of this object.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    Finalization is deprecated and subject to removal in a future release.
    final Class<?>
    getClass()
    Returns the runtime class of this Object.
    final void
    notify()
    Wakes up a single thread that is waiting on this object's monitor.
    final void
    notifyAll()
    Wakes up all threads that are waiting on this object's monitor.
    final void
    wait()
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
    final void
    wait(long timeoutMillis)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
    final void
    wait(long timeoutMillis, int nanos)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

  • Method Details

    • getKeyStroke

      public static KeyStroke getKeyStroke(char keyChar)
      Returns a shared instance of a KeyStroke that represents a KEY_TYPED event for the specified character.
      Parameters:
      keyChar - the character value for a keyboard key
      Returns:
      a KeyStroke object for that key

    • getKeyStroke

      @Deprecated public static KeyStroke getKeyStroke(char keyChar, boolean onKeyRelease)
      Deprecated.
      use getKeyStroke(char)
      Returns an instance of a KeyStroke, specifying whether the key is considered to be activated when it is pressed or released. Unlike all other factory methods in this class, the instances returned by this method are not necessarily cached or shared.
      Parameters:
      keyChar - the character value for a keyboard key
      onKeyRelease - true if this KeyStroke corresponds to a key release; false otherwise.
      Returns:
      a KeyStroke object for that key

    • getKeyStroke

      public static KeyStroke getKeyStroke(Character keyChar, int modifiers)
      Returns a shared instance of a KeyStroke 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 getKeyStroke(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 KeyStroke object for that key
      Throws:
      IllegalArgumentException - if keyChar is null
      Since:
      1.3
      See Also:

    • getKeyStroke

      public static KeyStroke getKeyStroke(int keyCode, int modifiers, boolean onKeyRelease)
      Returns a shared instance of a KeyStroke, 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 KeyStroke should represent a key release; false otherwise.
      Returns:
      a KeyStroke object for that key
      See Also:

    • getKeyStroke

      public static KeyStroke getKeyStroke(int keyCode, int modifiers)
      Returns a shared instance of a KeyStroke, given a numeric key code and a set of modifiers. The returned KeyStroke 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
      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
      Returns:
      a KeyStroke object for that key
      See Also:

    • getKeyStrokeForEvent

      public static KeyStroke getKeyStrokeForEvent(KeyEvent anEvent)
      Returns a KeyStroke 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 KeyStroke
      Returns:
      the KeyStroke that precipitated the event
      Throws:
      NullPointerException - if anEvent is null

    • getKeyStroke

      public static KeyStroke getKeyStroke(String s)
      Parses a string and returns a KeyStroke. 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" => getKeyStroke(KeyEvent.VK_INSERT, 0);
    "control DELETE" => getKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);
    "alt shift X" => getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);
    "alt shift released X" => getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);
    "typed a" => getKeyStroke('a');
      In order to maintain backward-compatibility, specifying a null String, or a String which is formatted incorrectly, returns null.
      Parameters:
      s - a String formatted as described above
      Returns:
      a KeyStroke object for that String, or null if the specified String is null, or is formatted incorrectly
      See Also: