Question

I tried this code:

public static void main(String[] args) throws Exception {
        String regexp = "[\\w-]+(\\.[\\w-]+)*@[\\w-]+(\\.[\\w-]+)*(\\.)[a-zA-Z]+";    

        String text1 = "[e-mail]";
        String text2 = "my.name-here@[e-mail]";
        String text3 = "@domain-here.ext";
        String text4 = "my.name-here@";
        String text5 = "my.name-here@domain-here";
        String text6 = "[e-mail]";
        String text7 = "[e-mail]";
        String text8 = "my.name-here@.my.domain-here.ext";
        String text9 = "[e-mail].";
        String text10 = "my.na [e-mail]";
        String text11 = "[e-mail] ain-here.ext";
        String text12 = "[e-mail]";
        String text13 = "my.name-here@my..domain-here.ext";

        RE re = new RE(regexp);
        System.out.println(re.match(text1));
        System.out.println(re.match(text2));
        System.out.println(re.match(text3));
        System.out.println(re.match(text4));
        System.out.println(re.match(text5));
        System.out.println(re.match(text6));
        System.out.println(re.match(text7));
        System.out.println(re.match(text8));
        System.out.println(re.match(text9));
        System.out.println(re.match(text10));
        System.out.println(re.match(text11));
        System.out.println(re.match(text12));
        System.out.println(re.match(text13));

        System.out.println(Pattern.matches(regexp, text1));
        System.out.println(Pattern.matches(regexp, text2));
        System.out.println(Pattern.matches(regexp, text3));
        System.out.println(Pattern.matches(regexp, text4));
        System.out.println(Pattern.matches(regexp, text5));
        System.out.println(Pattern.matches(regexp, text6));
        System.out.println(Pattern.matches(regexp, text7));
        System.out.println(Pattern.matches(regexp, text8));
        System.out.println(Pattern.matches(regexp, text9));
        System.out.println(Pattern.matches(regexp, text10));
        System.out.println(Pattern.matches(regexp, text11));
        System.out.println(Pattern.matches(regexp, text12));
        System.out.println(Pattern.matches(regexp, text13));
    }

Only the first one must be right but… org.apache.regexp.RE does something wrong. Any solution? Thanks a lot. I have to do it with org.apache.regexp.RE obligatory.

Update: Pattern do matches right (all false except the first one), RE say someone String are true but they isn’t.

Answer 1

Your expression does not state that it must match the entire input and thus I assume within my.name-here@[e-mail] Apache Regexp matches the [e-mail] part (although I don’t know Apache RegexP that well and it is retired, btw).

Wrap your regex with ^ and $ to make it match the entire input.

From the JavaDoc on Matcher#matches() (Pattern.matches(...) calls that method as you can see from its JavaDoc):

Attempts to match the entire region against the pattern

Edit

I just tested your expression in the RegexP applet and it seems like you have to escape the literal - in your character classes (which is good practice anyways). This expression seems to work in RegexP:

"^[\\w\\-]+(\\.[\\w\\-]+)*@[\\w\\-]+(\\.[\\w\\-]+)*(\\.)[a-zA-Z]+$"

Btw, you might want to add non-capturing groups to optimize the expression a bit, i.e. instead of (\\.) you’d write (?:\\.) etc.