From what I know of JFlex, if you are recognizing whitespaces corectly (which seems to be the case), you don't have to use extra states. Just make a rule for "identifiers", and another one for "numbers".
%%
{WORD} { return TokenType.WORD; }
{NUMBER} { return TokenType.NUMBER; }
If your language imposes each line to be consisted of exactly one identifier, one space and one number, this should be checked by syntactic analysis (i.e. by a parser), not lexical analysis.