[antlr-interest] how to define these characters(java)

[Nan Zhang]

I tried to build a parser and lexer (java) to do this simple task:
print every '+' encountered and ignore all other characters in the inputstream(or maybe do other actions instead of just ignore it).
Here's my code:
-----------
class P extends Parser;
options {
 defaultErrorHandler = false;
 }
startRule 
 : 
     (n:PLUS {System.out.println(n.getText())}
     )+ NEWLINE
 ;

class L extends Lexer;
PLUS : '+' ;
NEWLINE : '\r''\n'|'\n' ;
NON : ~('+'|'\r''\n'|'\n') {$setType(Token.SKIP); }//and other actions
 ;
------------
but I got an error message: This subrule cannot be inverted. Only subrules of the form:
    (T1|T2|T3...) or
    ('c1'|'c2'|'c3'...)
may be inverted (ranges are also allowed).
Exiting due to errors.

I know there must be something wrong with NON definition in my code, but how to define such a characterSet: not '+' and not newline?
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