Hackerrank Java Substring Comparisons

Hackerrank Java Substring Comparisons.java

import java.util.Scanner;
public class Solution {
public static String getSmallestAndLargest(String s, int k) {
        String smallest = "";
        String largest = "";
        smallest = largest = s.substring(0,k);
        
//      "Compare to" method doesn't turn just the equel case it also turns a value.

        for(int i=0; i<=s.length()-k+1; i++ ){
            String str = s.substring(i,k+i);
            if (smallest.compareTo(str)>0){
                smallest = str;
            }
            if(largest.compareTo(str)<0){
                largest=str;
            }
        }  
        return smallest + "\n" + largest;
    }
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String s = scan.next();
        int k = scan.nextInt();
        scan.close();
      
        System.out.println(getSmallestAndLargest(s, k));
    }
}