This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
An identifier is an unlimited-length sequence of Java letters and Java digits, the
first of which must be a Java letter.
IdentifierChars but not a Keyword or BooleanLiteral or NullLiteral
any Unicode character that is a Java letter (see below)
any Unicode character that is a Java letter-or-digit (see below)
A "Java letter" is a character for which the method
Character.isJavaIdentifierStart(int) returns true.
A "Java letter-or-digit" is a character for which the method
Character.isJavaIdentifierPart(int) returns true.