Regex and StringTokenizer Syntax Error

Question

I'm new to regular expressions and StringTokenizer, and I'm getting a syntax error whenever I put this regex in matches:

while ((line = br.readLine()) != null) { 
    StringTokenizer stringTokenizer = new StringTokenizer(line, "\n");

    while (stringTokenizer.hasMoreElements()) {
        String function = stringTokenizer.nextElement().toString();

        if (function.matches(\\s*(unsigned int|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;)) {
            System.out.println("VALID - ");
        }
    }
}

Maybe a copy and paste error, but it could be that you're missing the quotes around your regex to make it a `String`. — Brian, Jan 28 '13 at 02:10
FYI from the [docs](http://docs.oracle.com/javase/7/docs/api/java/util/StringTokenizer.html): "`StringTokenizer` is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the `split` method of `String` or the java.util.regex package instead." — Paul Bellora, Jan 28 '13 at 02:32
Must be lack of sleep, but thanks Brian! It works now -.- The tutorial I was reading online didn't place quotations and I don't know why it didn't occur to me that t needed some. Cheers! — Pau, Jan 28 '13 at 03:55
@Brian You should post your comment as an answer so it can be accepted. — Jim Garrison, Jan 28 '13 at 09:01

score 0 · Answer 1 · answered Jan 28 '13 at 16:49

Maybe a copy and paste error, but it could be that you're missing the quotes around your regex to make it a String. For example:

while ((line = br.readLine()) != null) { 
    StringTokenizer stringTokenizer = new StringTokenizer(line, "\n");

    while (stringTokenizer.hasMoreElements()) {
        String function = stringTokenizer.nextElement().toString();

        if (function.matches("\\s*(unsigned int|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;")) {
            System.out.println("VALID - ");
        }
    }
}

score 0 · Answer 2 · answered Jan 28 '13 at 17:07

matches method takes String as method argument... So, enclose your regex withing quoutes " " like this:

function.matches("\\s*(unsigned int|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;)")

score 0 · Accepted Answer · answered Jan 28 '13 at 17:38

enclose your string withing quotes " ", And note that when using the operator "or" (|) for two consecutive words, we should use them in parenthesis ((unsigned int) | float)

while ((line = br.readLine()) != null) { 
StringTokenizer stringTokenizer = new StringTokenizer(line, "\n");

while (stringTokenizer.hasMoreElements()) {
    String function = stringTokenizer.nextElement().toString();

    if (function.matches("\\s*((unsigned int)|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;")) {
        System.out.println("VALID - ");
    }
}

}

Regex and StringTokenizer Syntax Error

3 Answers3