20.5

java.lang.Character

THE PACKAGE JAVA.LANG

20.5.13

public static boolean isTitleCase(char ch)

The result is

true

 if and only if the character argument is a titlecase character.

The notion of  titlecase  was introduced into Unicode to handle a peculiar sit 

uation: there are single Unicode characters whose appearance in each case looks

exactly like two ordinary Latin letters. For example, there is a single Unicode

character `LJ' (

\u01C7

) that looks just like the characters `L' and `J' put together.

There is a corresponding lowercase letter `lj' (

\u01C9

) as well. These characters

are present in Unicode primarily to allow one to one translations from the Cyrillic

alphabet, as used in Serbia, for example, to the Latin alphabet. Now suppose the

word  LJUBINJE  (which has

six

 characters, not eight, because two of them are

the single Unicode characters `LJ' and `NJ', perhaps produced by one to one

translation from the Cyrillic) is to be written as part of a book title, in capitals and

lowercase. The strategy of making the first letter uppercase and the rest lowercase

results in  LJubinje  most unfortunate. The solution is that there must be a third

form, called a

titlecase

 form. The titlecase form of `LJ' is `Lj' (

\u01C8

) and the

titlecase form of `NJ' is `Nj'. A word for a book title is then best rendered by con 

verting the first letter to titlecase if possible, otherwise to uppercase; the remain 

ing letters are then converted to lowercase.

A character is considered to be titlecase if and only if both of the following

are true:

The character

ch

 is not in the range

\u2000

 through

\u2FFF

.

The Unicode attribute table specifies a mapping to uppercase

and

 a mapping

to lowercase for this character.

There are exactly four Unicode 1.1.5 characters for which

isTitleCase

 returns

true

:

\u01C5

LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON

\u01C8

LATIN CAPITAL LETTER L WITH SMALL LETTER J

\u01CB

LATIN CAPITAL LETTER N WITH SMALL LETTER J

\u01F2

LATIN CAPITAL LETTER D WITH SMALL LETTER Z

[This method is scheduled for introduction in Java version 1.1, either as

defined here, or updated for Unicode 2.0; see  20.5.]

20.5.14

public static boolean isDigit(char ch)

The result is

true

 if and only if the character argument is a digit.

A character is considered to be a digit if and only if both of the following are

true:

478