Question

I need validate a String using a Regular Expression, the String must be like “createRobot(x,y)”, where x and y are digits.

I have Something like

    String ins; 

    Pattern ptncreate= Pattern.compile("^createRobot(+\\d,\\d)");
    Matcher m = ptncreate.matcher(ins);
    System.out.println(m.find());

but doesn’t work

Can you help me ?.

Thanks.

Answer 1

You forgot the word Robot in your pattern. Also, parenthesis are special characters in regex, and the + should be placed after the \d, not after a (:

Pattern.compile("^createRobot\\(\\d+,\\d+\\)$")

Note that if you want to validate input that should consist solely of this "createRobot"-string, you mind as well do:

boolean success = s.matches("createRobot\\(\\d+,\\d+\\)");

where s is the String you want to validate. But if you want to retrieve the numbers that were matched, you do need to use a Pattern/Matcher:

Pattern p = Pattern.compile("createRobot\\((\\d+),(\\d+)\\)");
Matcher m = p.matcher("createRobot(12,345)");
if(m.matches()) {
  System.out.printf("x=%s, y=%s", m.group(1), m.group(2));
}

As you can see, after calling Matcher.matches() (or Matcher.find()), you can retrieve the n^th match-group through group(n).