今日课程：

<code class="java">class Supermarket {
    private int price; // Instance variables, using private for better encapsulation
    private int discount;
    private String productName;

    // Parameterized constructors
    public Supermarket(String productName, int price, int discount) {
        this.price = price;
        this.discount = discount;
        this.productName = productName;
    }

    public Supermarket(String productName, int price) {
        this.price = price;
        this.productName = productName;
        this.discount = 0; // Default discount if not provided
    }

    public static void main(String[] args) {
        Supermarket product1 = new Supermarket("Good Day", 10, 2);
        Supermarket product2 = new Supermarket("Rice", 55);

        System.out.println(product1.getProductName()); // Accessing using getter method
        System.out.println(product2.getProductName());

        product1.buy();
        product1.returnProduct();
    }

    // Methods for better readability and maintainability
    public void buy() {
        System.out.println("Buying " + productName + " for " + (price - discount));
    }

    public void returnProduct() {
        System.out.println("Returning " + productName + " for " + price);
    }

    // Getter method for productName
    public String getProductName() {
        return productName;
    }
}</code>