Java Syntax - Java Software Solutions: Foundations of Program Design - page 731

Identifier

Java Letter

Java Letter
Java Digit

Java Letter

a - z
A - Z
_
$

other Java letter *

Unicode Escape

* The "other Java letter" category includes letters
from many languages other than English.

Java Digit

0 - 9

other Java digit *

Unicode Escape

* The "other Java digit" category includes
additional digits defined in Unicode.

Unicode Escape*

\ u Hex Digit Hex Digit Hex Digit Hex Digit

* In some contexts, the character represented
by a Unicode Escape is restricted.