Design a Product class that includes the properties of product’s ID, price, number of sold (當噺的沌噽). The class has the following operations: 1. Revenue: calculates the total revenue (噷當噺噻) of all products. 2. toString: returns the values of all the attributes of a Prodect object. 3. Output: output the product information by using toString(). Requirement: 1. The class must have a constructor with parameters; 2. Write a test program that declares three objects. One of these objects is declared by using your student No (学噼) as product‘s ID.

下面是一个符合要求的Java代码实现：

public class Product {
    private String ID;
    private double price;
    private int quantitySold;

    public Product(String ID, double price, int quantitySold) {
        this.ID = ID;
        this.price = price;
        this.quantitySold = quantitySold;
    }

    public double revenue() {
        return price * quantitySold;
    }

    public String toString() {
        return "Product ID: " + ID + ", Price: " + price + ", Quantity Sold: " + quantitySold;
    }

    public static void main(String[] args) {
        Product p1 = new Product("12345", 19.99, 100);
        Product p2 = new Product("67890", 29.99, 50);
        Product p3 = new Product("2021123456", 9.99, 200);

        System.out.println(p1.toString());
        System.out.println(p2.toString());
        System.out.println(p3.toString());
    }
}

在main方法中，我们创建了三个Product对象，其中一个的ID是学号。然后我们调用了每个对象的toString方法来打印出它们的属性信息。运行上述代码，输出结果如下：

Product ID: 12345, Price: 19.99, Quantity Sold: 100
Product ID: 67890, Price: 29.99, Quantity Sold: 50
Product ID: 2021123456, Price: 9.99, Quantity Sold: 200