Java language and no hard coding please . i need answer for P6.31 only. questionis related with above question so i post together so it can be understand easily.

A supermarket wants to reward its best customer of each day, showing the customers name on a screen in the supermarket. For that purpose, the customers purchase amount is stored in an ArrayList and the customers name is stored in a corresponding ArrayList. Implement a method public static String nameOfBestCustomer(ArrayList sales, ArrayList customers) that returns the name of the customer with the largest sale. Write a program that prompts the cashier to enter all prices and names, adds them to two array lists, calls the method that you implemented, and displays the result. Use a price of 0 as a sentinel. Business

P6.31 Improve the program of Exercise P6.30 so that it displays the top customers, that is, the topN customers with the largest sales, where topN is a value that the user of the program supplies. Implement a method public static ArrayList nameOfBestCustomers(ArrayList sales, ArrayList customers, int topN) If there were fewer than topN customers, include all of them.