Extract Numbers

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String s = sc.nextLine();

        StringBuilder digits = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            if (Character.isDigit(s.charAt(i))) {
                digits.append(s.charAt(i));
            }
        }
        System.out.println("Digits: " + digits.toString());
        sc.close();
    }
}