by using JAVA Exercise:

Consider a superclass PurchaseItem which models customers purchases. This class has:

• two private instance variables name (String) and unitPrice (double).
• One constructor to initialize the instance variables.
• A default constructor to initialize name to no item, and unitPrice to 0. use this()
• A method getPrice that returns the unitPrice.
• Accessor and mutator methods.
• A print method to return the name of the item followed by @ symbol, then the unitPrice.

Consider two subclasses WeighedItem and CountedItem. 

WeighedItem has an additional instance variable weight (double) in Kg while CountedItem has an additional variable quantity (int) both private.

- Write an appropriate constructor for each of the classes making use of the constructor of the superclass in defining those of the subclasses. 

- Override getPrice method that returns the price of the purchasedItem based on its unit price and weight (WeighedItem), or quantity (CountedItem). Make use of getPrice of the superclass

- Override also toString method for each class making use of the toString method of the superclass in defining those of the subclasses.

toString should return something that can be printed on the receipt.

For example 

Banana @ 3.00 1.37Kg 4.11 SR (in case of WeighedItem class)

Pens @ 4.5 10 units 45 SR (in case of CountedItem class) 

Write an application class where you construct objects from the two subclasses and print them on the screen.