Inventory Part 2 Portion And Getting Errors

for my assignment I am to only add the sort and total inventory methods in the inventory class. And not create an array in the inventory class at all. My inventory class should contain all the variables needed to use with the two new methods: sort and calculate total inventory.By not creating any array in the inventory class and not touching the variables at all.For the inventoryTest class, I only need to declare an array of the inventory class by making an instance of the inventory.

public class inventory
{

private int prodNumber; // product number
private String prodName; // product name
private int unitsTotal; // total units in stock
private double unitPrice; // price per unit
private double totalInventory; // amount of total inventory

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