Java REGEX to match an exact number of digits in a string

Question

I tried to find the answer to my problem in the questions history but they just come back in more than one thousand and after scanning through a few tens of matching answers

Answer 1

 public static String splitting(String str, int num){
    String arr[] = str.split("[^0-9]");
    for(String s:arr)
        if(s.length() == num)
            return s;
    return null;
}

test with

 public static void main(String[] args) {
    String s =  "Some text 987654321 and some more text 123456 and some other text again 654321 and more text in the end";
    System.out.println(splitting(s, 6));
}

output is

  123456