if ( lexer==null ) {
lexer = new JavaLexer();
}
lexer.setCharStream(new ANTLRFileStream(f));
CommonTokenStream tokens = new CommonTokenStream();
tokens.discardOffChannelTokens(true);
tokens.setTokenSource(lexer);
long start = System.currentTimeMillis();
tokens.LT(1); // force load
long stop = System.currentTimeMillis();
lexerTime += stop-start;