Java Program Invoice Class

(Invoice Class) 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 a constructor that initializes the four 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 app named InvoiceTest that demonstrates class Invoice’s capabilities.

java invoice application source code

Invoice.java

/*
 *       Filename:  Invoice.java
 *
 *    Description:  Exercise 3.13 - Invoice Class
 *
 *  @Author:  Bilal Tahir Khan Meo
 *  Website: https://codeblah.com
 *
 * =====================================================================================
 */
public class Invoice{
    private String partNumber;
    private String partDescription;
    private int quantity;
    private double unitPrice;

    // constructor
    public Invoice(String partNumber, String partDescription, int quantity, double unitPrice){

        setPartNumber(partNumber);
        setDescription(partDescription);
        setQuantity(quantity);
        setUnitPrice(unitPrice);
    }
    // setters
    public void setPartNumber(String partNumber){
        this.partNumber = partNumber;
    }
    public void setDescription(String partDescription){
        this.partDescription = partDescription;
    }
    public void setQuantity(int quantity){
        this.quantity = (quantity < 0) ? 0 : quantity;
    }
    public void setUnitPrice(double unitPrice){
        this.unitPrice = (unitPrice < 0.0) ? 0.0 : unitPrice;
    }
    // getters
    public String getPartNumber(){
        return partNumber;
    }
    public String getDescription(){
        return partDescription;
    }
    public int getQuantity(){
        return quantity;
    }
    public double getUnitPrice(){
        return unitPrice;
    }
    public double getInvoiceAmount(){
        return getQuantity() * getUnitPrice();
    }
}

InvoiceTest.java

/*
 *       Filename:  InvoiceTest.java
 *
 *    Description:  Exercise 3.13 - Invoice Class
 *
 *  @Author:  Bilal Tahir Khan Meo
 *  Website: https://codeblah.com
 *
 * =====================================================================================
 */
public class InvoiceTest{
    public static void main(String[] args){
        // testing positive values
        Invoice spanner = new Invoice("123", "A Spanner", 15, 12.5);

        printInvoice(spanner.getPartNumber(), spanner.getDescription(),
                     spanner.getQuantity(), spanner.getUnitPrice(),
                     spanner.getInvoiceAmount());

        // testing negative values
        Invoice hammer = new Invoice("124", "A Hammer", -1, -15.0);

        printInvoice(hammer.getPartNumber(), hammer.getDescription(),
                     hammer.getQuantity(), hammer.getUnitPrice(),
                     hammer.getInvoiceAmount());

    }
    // print invoice
    private static void printInvoice(String num, String desc,
                                int quan, double price, double total){
        System.out.printf("%s: %s - %d * %.2f = %.2f\n", num, desc, quan, price, total);
    }
}

java invoice application source code

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