Please use java to give the solutions,thanks.
a. Write a program that allows you to create a file of customers for a company. The first part of the program should create an empty file suitable for writing a three-digit ID number, six-character last name, and five-digit zip code for each customer.
The second half of the program accepts user input to populate the file. For this exercise, assume that the user will correctly enter ID numbers and zip codes, but force the customer name to seven characters if it is too long or too short.
Issue an error message, nd do not save the records if the user tries to save a record with an ID number that has already been used. Save the program as CreateCustomerFile.java.
b. Write a program that creates a file of items carried by the company. Include a three-digit item number and up to a 20-character description for each item. Issue an error message if the user tries to store an item number that has already been used. Save the program as CreateItemFile.java.
c. Write an application that takes customer orders. Allow a user to enter a customer number and item ordered. Display an error message if the customer number does not exist in the customer file or the item does not exist in the item file; otherwise, display all the customer information and item information.