Counting integers in a string

String s = "abcd123";
    int counter = 0;
    for(char c : s.toCharArray()) 
    {
        if( c >= '0' && c<= '9') 
        {
            ++counter;
        }
    }

OR

String s = "abcd123";
int count = 0;
for (int i = 0, len = s.length(); i < len; i++) 
{
    if (Character.isDigit(s.charAt(i))) 
    {
        count++;
    }
}