Product.java

public abstract class Product implements Comparable<Product> {
    private final double price;
    private int stockQuantity;
    private int soldQuantity;
    private int totalRevenue = 0;
    private int cartQuantity;

    public Product (double InitPrice, int InitStockQuantity) {
        price = InitPrice;
        stockQuantity = InitStockQuantity;
        soldQuantity = 0;
        cartQuantity = 0;
    }
    //get methods
    public double getPrice() {
        return price;
    }
    public int getSoldQuantity() {
        return soldQuantity;
    }
    public int getStockQuantity() {
        return stockQuantity;
    }
    public int getCartQuantity() {
        return cartQuantity;
    }
    public int getTotalRevenue() {return totalRevenue;}
    //set method
    public void setCartQuantity(int cartQuantity) {
        this.cartQuantity = cartQuantity;
    }
    //adjust stock and sold quantities and update the products own revenue
    public void sellUnits(int amount) {
        if (stockQuantity >= amount) {
            stockQuantity -= amount;
            soldQuantity += amount;
            totalRevenue += (amount * price);
        }
    }

    @Override
    public int hashCode() {
        return -1;
    }

    @Override
    public int compareTo(Product o) {
        return o.getSoldQuantity() - soldQuantity;
    }

}