Returns:

true if the character is a digit; false otherwise.

Parameters:

ch - the character to be tested

A character may start a Java identifier if and only if it is one of the following:

• a letter
• a currency symbol (such as "$")
• a connecting punctuation symbol (such as "_").

A character may be part of a Java identifier if and only if it is one of the following:

• a letter
• a currency symbol (such as "$")
• a connecting punctuation character (such as "_").
• a digit
• a numeric letter (such as a Roman numeral character)
• a combining mark
• a non-spacing mark
• an ignorable control character

A character may be part of a Unicode identifier if and only if it is one of the following:

• a letter
• a connecting punctuation character (such as "_").
• a digit
• a numeric letter (such as a Roman numeral character)
• a combining mark
• a non-spacing mark
• an ignorable control character

The following Unicode characters are ignorable in a Java identifier or a Unicode identifier:

0x0000 through 0x0008,	ISO control characters that
0x000E through 0x001B,	are not whitespace
and 0x007F through 0x009F
0x200C through 0x200F	join controls
0x200A through 0x200E	bidirectional controls
0x206A through 0x206F	format controls
0xFEFF	zero-width no-break space

A character has a lowercase equivalent if and only if a lowercase mapping is specified for the character in the Unicode 2.0 attribute table.

Unicode::toLowerCase() only deals with the general letter case conversion. For language specific case conversion behavior, use UnicodeString::toLower(). For example, the case conversion for dot-less i and dotted I in Turkish, or for final sigma in Greek.

Unicode::toUpperCase() only deals with the general letter case conversion. For language specific case conversion behavior, use UnicodeString::toUpper(). For example, the case conversion for dot-less i and dotted I in Turkish, or ess-zed (i.e., "sharp S") in German.

A character has a titlecase equivalent if and only if a titlecase mapping is specified for the character in the Unicode 2.1.2 data.

Returns:

true if the character is a space character; false otherwise.

Parameters:

ch - the character to be tested

ZERO_WIDTH: Characters which are considered to take up no display-cell space: control characters format characters line and paragraph separators non-spacing marks combining Hangul jungseong combining Hangul jongseong unassigned Unicode values

HALF_WIDTH: Characters which take up half a cell in standard Asian text: all characters in the General Scripts Area except combining Hangul choseong and the characters called out specifically above as ZERO_WIDTH alphabetic and Arabic presentation forms halfwidth CJK punctuation halfwidth Katakana halfwidth Hangul Jamo halfwidth forms, arrows, and shapes

FULL_WIDTH: Characters which take up a full cell in standard Asian text: combining Hangul choseong all characters in the CJK Phonetics and Symbols Area all characters in the CJK Ideographs Area all characters in the Hangul Syllables Area CJK compatibility ideographs CJK compatibility forms small form variants fullwidth ASCII fullwidth punctuation and currency signs

NEUTRAL: Characters whose cell width is context-dependent: all characters in the Symbols Area, except those specifically called out above all characters in the Surrogates Area all charcaters in the Private Use Area

For Korean text, this algorithm should work properly with properly normalized Korean text. Precomposed Hangul syllables and non-combining jamo are all considered full- width characters. For combining jamo, we treat we treat choseong (initial consonants) as double-width characters and junseong (vowels) and jongseong (final consonants) as non-spacing marks. This will work right in text that uses the precomposed choseong characters instead of teo choseong characters in a row, and which uses the choseong filler character at the beginning of syllables that don't have an initial consonant. The results may be slightly off with Korean text following different conventions.

Returns:

the numeric value of ch in decimal radix. This method returns -1 if ch is not a valid digit character.

Parameters:

ch - the digit character for which to get the numeric value

Returns:

the Unicode Standard Version Number.