Collection.java

import java.util.ArrayList;  
 import java.util.Collections;  
 import java.util.List;  
 import java.util.Scanner;  
 /**  
  * @author Dixit  
  *   
  */  
 public class Collection {  
      public static void main(String a[]) {  
           Scanner sc = new Scanner(System.in);  
           System.out.println("Enter the String:-");  
           String str = sc.nextLine();  
           System.out.println("Enter the length");  
           int count = sc.nextInt();  
           List<String> list = new ArrayList<String>();  
           for (int i = 0; i < str.length(); i = i + 1) {  
                if (str.length() - i >= count) {  
                     list.add(str.substring(i, count + i));  
                }  
           }  
           Collections.sort(list);  
           System.out.println("Smallest subString:-" + list.get(0));  
           System.out.println("Largest subString:-" + list.get(list.size() - 1));  
      }  
 }