Find count of digits in string variable

Question

I have a string which sometimes gives character value and sometimes gives integer value. I want to get the count of number of digits in that string.

For example, if string contains "2485083572085748" then total number of digits is 16.

Please help me with this.

Answer 1

A cleaner solution using Regular Expressions:

// matches all non-digits, replaces it with "" and returns the length.
s.replaceAll("\\D", "").length()

Answer 2

String s = "2485083572085748";
int count = 0;
for (int i = 0, len = s.length(); i < len; i++) {
    if (Character.isDigit(s.charAt(i))) {
        count++;
    }
}

Answer 3

Just to refresh this thread with stream option of counting digits in a string:

"2485083572085748".chars()
                  .filter(Character::isDigit)
                  .count();

Answer 4

If your string gets to big and full of other stuff than digits you should try to do it with regular expressions. Code below would do that to you:

String str = "asdasd 01829898 dasds ds8898";

Pattern p = Pattern.compile("\d"); // "\d" is for digits in regex
Matcher m = p.matcher(str);
int count = 0;
while(m.find()){
   count++;
}

check out java regex lessons for more. cheers!