JLS says that only ASCII digits may be used in number literals and various escape sequences, e.g. \udddd, \xdd, etc.

javac checks for ASCII digits, but only gives a warning if non-ASCII digits are found: given the JLS statement, it should give an error.
###@###.### 10/23/04 00:36 GMT
###@###.### 2005-1-26 07:03:37 GMT