org.gnome.gdk
Class Keyval

Object
  org.freedesktop.bindings.Constant
      org.gnome.gdk.Keyval

Direct Known Subclasses:

KeypadKeyval

public class Keyval
extends org.freedesktop.bindings.Constant

A key value as returned by a keyboard Event. Handling keystrokes is not as much fun as you might think. There is considerable complexity associated with dealing with language and country specific keyboard variants. Most of this complexity is, however, dealt with for you by the X server as proxied by GDK. This class, in turn, provides constants for the basic keyboard set. Various subclasses give you access to localized keyboards.

It is important to note that lower case and upper case letters are considered different keys even though most keyboards present but a single physical button with an A showing. Think of that physical key as having both an a and an A printed on it, with the second being the key reached if the Shift modifier is held down. Have a look at the ModifierType class for a discussion of how to deal with the modifying keys and for a better understanding of the sequence in which key events occur.

Looking for 1 through 9? See Num0 to Num9.

The correlation between keys and Unicode characters is a complex one. For basic western ISO Latin letters the keys we press and the characters we get are, to all intents and purposes, one and the same. But there are many thousands of additional characters for which you probably don't have keys for, even if you have (or have mapped something to be) the Compose key for taking the composite of several keystrokes to generate special characters. Just remember that Keyvals are key constants, not constants for every unicode character and you'll keep things straight.

GDK deals with keyvals exclusively as ints, and there are over 1700 of them. Most of these "keys" are ridiculous or apply to hardware that has long since ceased to exist. We've deliberately constrained this class to a narrow range; experience in 2.x showed that even mighty Eclipse chokes when asked to complete from a list that big. This leads us to two consequences. 1) Constants will be registered for keyvals encountered that haven't been explicitly created here, so you don't have to worry about some nasty RuntimeException kicking your ass. 2) You can extend this Keyval class as necessary to create your own constants if you need to. See KeypadKeyval for an example.

Since:

4.0.6

Author:

Andrew Cowie

a

public static final Keyval a

A

public static final Keyval A

AltLeft

public static final Keyval AltLeft

AltRight

public static final Keyval AltRight

Ampersand

public static final Keyval Ampersand

Apostrophe

public static final Keyval Apostrophe

Asterisk

public static final Keyval Asterisk

AtSign

public static final Keyval AtSign

b

public static final Keyval b

B

public static final Keyval B

Backslash

public static final Keyval Backslash

BackSpace

public static final Keyval BackSpace

BackTab

public static final Keyval BackTab

Reverse indentation key.

This occurs on when you type Shift+Tab. Normal (forward) indentation keystrokes are the Tab Keyval.

Backwards movement by an indent is a legacy from the age of typewriters, and not used in text entry today. The Shift+Tab sequence is, however, used in GNOME to move the keyboard focus one Widget back.

Since:

4.0.14

Bar

public static final Keyval Bar

Also known as Pipe (from the fact that this is used in a Unix shell to "pipe" output from one command to another).

BraceLeft

public static final Keyval BraceLeft

BraceRight

public static final Keyval BraceRight

BracketLeft

public static final Keyval BracketLeft

BracketRight

public static final Keyval BracketRight

Break

public static final Keyval Break

c

public static final Keyval c

C

public static final Keyval C

CapsLock

public static final Keyval CapsLock

Circumflex

public static final Keyval Circumflex

Also known as Carrot or Hat.

Colon

public static final Keyval Colon

Comma

public static final Keyval Comma

Compose

public static final Keyval Compose

The Compose used to create high order characters from pressing tis plus certain following key sequences.

Since:

4.0.11

ControlLeft

public static final Keyval ControlLeft

ControlRight

public static final Keyval ControlRight

d

public static final Keyval d

D

public static final Keyval D

Delete

public static final Keyval Delete

Dollar

public static final Keyval Dollar

Down

public static final Keyval Down

e

public static final Keyval e

E

public static final Keyval E

End

public static final Keyval End

Equal

public static final Keyval Equal

Escape

public static final Keyval Escape

Exclaim

public static final Keyval Exclaim

f

public static final Keyval f

F

public static final Keyval F

F1

public static final Keyval F1

F10

public static final Keyval F10

F11

public static final Keyval F11

F12

public static final Keyval F12

F2

public static final Keyval F2

F3

public static final Keyval F3

F4

public static final Keyval F4

F5

public static final Keyval F5

F6

public static final Keyval F6

F7

public static final Keyval F7

F8

public static final Keyval F8

F9

public static final Keyval F9

g

public static final Keyval g

G

public static final Keyval G

Grave

public static final Keyval Grave

Greater

public static final Keyval Greater

h

public static final Keyval h

H

public static final Keyval H

Home

public static final Keyval Home

i

public static final Keyval i

I

public static final Keyval I

Insert

public static final Keyval Insert

j

public static final Keyval j

J

public static final Keyval J

k

public static final Keyval k

K

public static final Keyval K

l

public static final Keyval l

L

public static final Keyval L

Left

public static final Keyval Left

Less

public static final Keyval Less

m

public static final Keyval m

M

public static final Keyval M

Menu

public static final Keyval Menu

Minus

public static final Keyval Minus

n

public static final Keyval n

N

public static final Keyval N

Num0

public static final Keyval Num0

Num1

public static final Keyval Num1

Num2

public static final Keyval Num2

Num3

public static final Keyval Num3

Num4

public static final Keyval Num4

Num5

public static final Keyval Num5

Num6

public static final Keyval Num6

Num7

public static final Keyval Num7

Num8

public static final Keyval Num8

Num9

public static final Keyval Num9

NumberSign

public static final Keyval NumberSign

NumLock

public static final Keyval NumLock

o

public static final Keyval o

O

public static final Keyval O

p

public static final Keyval p

P

public static final Keyval P

PageDown

public static final Keyval PageDown

PageUp

public static final Keyval PageUp

ParenLeft

public static final Keyval ParenLeft

ParenRight

public static final Keyval ParenRight

Pause

public static final Keyval Pause

Percent

public static final Keyval Percent

Period

public static final Keyval Period

Plus

public static final Keyval Plus

Print

public static final Keyval Print

q

public static final Keyval q

Q

public static final Keyval Q

Question

public static final Keyval Question

QuoteDouble

public static final Keyval QuoteDouble

QuoteSingle

public static final Keyval QuoteSingle

r

public static final Keyval r

R

public static final Keyval R

Return

public static final Keyval Return

Right

public static final Keyval Right

s

public static final Keyval s

S

public static final Keyval S

ScrollLock

public static final Keyval ScrollLock

Semicolon

public static final Keyval Semicolon

ShiftLeft

public static final Keyval ShiftLeft

ShiftRight

public static final Keyval ShiftRight

Slash

public static final Keyval Slash

Space

public static final Keyval Space

SuperLeft

public static final Keyval SuperLeft

SuperRight

public static final Keyval SuperRight

SysReq

public static final Keyval SysReq

t

public static final Keyval t

T

public static final Keyval T

Tab

public static final Keyval Tab

Normal indentation key.

In normal GNOME user interface usage, this is used to move the keyboard focus forwards from one Widget to the next. In text documents, however, Tab is typically used to insert a '\t' character.

Be aware that on a standard GNOME desktop, Alt+Tab is captured by the window manager used to change between applications, so you likely won't receive it.

Tilde

public static final Keyval Tilde

u

public static final Keyval u

U

public static final Keyval U

Underscore

public static final Keyval Underscore

Up

public static final Keyval Up

v

public static final Keyval v

V

public static final Keyval V

w

public static final Keyval w

W

public static final Keyval W

x

public static final Keyval x

X

public static final Keyval X

y

public static final Keyval y

Y

public static final Keyval Y

z

public static final Keyval z

Z

public static final Keyval Z

toUnicode

public char toUnicode()

Translate this Keyval to a unicode representation. This is useful when you've intercepted a keystroke and, having determined it is a "normal" character and not something more unusual, need to append it to a String.

One way this might be used is:

 final Pattern regexAtoZ = Pattern.compile("[a-z]");
 final Keyval key;
 final String str, result;
 
 str = "" + key.toUnicode();
 
 if (key == Keyval.Return) {
     // execute
 } else if (key == Keyval.Escape) {
     // abort
 } else if (regexAtoZ.matcher(str).matches()) {
     entry.setText(str);
 } else {
     ...
 }
 

which is a bit cumbersome, but illustrates one way of identifying "normal" letters being typed.

Not all keys have translations; in such cases 0 will be returned. Testing for this can sometimes be an easier approach to figuring out if a "normal" key was hit, but your mileage will vary depending on the user's actual configuration. Note that that's (char) 0, not '0'!

Be wary of appending this return value to a String!
Although Java won't lose the character or subsequent ones, \0 is the "NULL terminator" for char* strings in C and will prematurely terminate the printed output if you try to print the String (as, after all, in the final analysis the Java VM is nothing more than a C program and eventually a C library routine will be called to output the text)!

Since:

4.0.6

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