Assignment

1. Create a class called Invoice that a hardware store might use to represent an invoice for an item sold at the store. An Invoice should include four pieces of information as instance variables-a part number (type String), a part description (type String), a quantity of the item being purchased (type int) and a price per item (double).

Your class should have two overloaded constructors: one as zero argument constructor and the other as a 4 argument constructor, for initializing the instance variables.

Provide a set and a get method for each instance variable. In addition, provide a method named getInvoiceAmount that calculates the invoice amount (i.e., multiplies the quantity by the price per item), then returns the amount as a double value. If the quantity is not positive, it should be set to 0. If the price per item is not positive, it should be set to 0.0.
Write a test application named InvoiceTest (a driver class) that demonstrates class Invoice's capabilities. Try and demonstrate use of all the constructors & methods in the class. Take print screen of the output of the driver class.

2. Create a class called Date that includes three instance variables-a month (type int), a day (type int) and a year (type int). Provide a three argument constructor that initializes the three instance variables and assumes that the values provided are correct. Provide a set and a get method for each instance variable. Provide a method displayDate that displays the month, day and year separated by forward slashes (/).Write a test application named DateTest (a driver class) that demonstrates class Date's capabilities and the use of "this" reference. Try and demonstrate use of all the constructors & methods in the class. Take print screen of the output of the driver class.