Inheritance problem

[paquizzle]

I have literally been stuck for almost 24 hours with no progress, so that is why I am here. I have 3 Java programs that I have written. They are Order.java, ShippedOrder.Java and UseOrder.Java. The UseOrder has the main method and it uses the other 2. It asks for input about a purchase order, which I get the data back correctly, but then it asks about adding shipping and handling, and when I do that, it returns all fields back as 0 or null except for the shipping cost field. I know that it is an inheritance problem, but I cannot figure out what I need to change to make it work properly.


Here is the parent class

import java.util.Scanner; 
public class Order  
{  
    protected String customerName;  
    protected int customerNum, quantity;  
    protected double unitPrice, totalPrice;  
    Scanner input = new Scanner(System.in);

    public String getCustomerName()  
    {  
        return customerName;  
    }  
    public void setCustomerName()  
    {  
        System.out.println("Please enter customer name.");
        customerName = input.nextLine();  
    }  

    public int getCustomerNum()  
    {  
        return customerNum;  
    }  
    public void setCustomerNum()  
    {  
        System.out.println("Please enter customer number.");
        customerNum = input.nextInt();  
    }  

    public int getQuantity()  
    {  
        return quantity;  
    }  
    public void setQuantity()  
    {  
        System.out.println("Please enter quantity ordered.");
        quantity = input.nextInt();  
    }  

    public double getUnitPrice()  
    {  
        return unitPrice;  
    }  
    public void setUnitPrice()  
    { 
        System.out.println("Please enter unit price."); 
        unitPrice = input.nextDouble();  
    }  

    public void computePrice()  
    {  
        totalPrice = quantity * unitPrice;  
    }  

    public void displayInfo()  
    {  
        System.out.println("Customer Name : " +  
           customerName + "\nCustomer Number : " + customerNum +  
           "\nQuantity Ordered : " + quantity + "\nUnit Price : $" +  
           unitPrice  + "\nTotal Price : $" + totalPrice);  
    }  
}

The child class

import java.util.Scanner;  
public class ShippedOrder extends Order  
{  
    private double extraCharge = 4;  
    private double totalPrice1;  
    private String customerName1 = super.getCustomerName();  
    private int customerNum1 = super.getCustomerNum();  
    private int quantity1 = super.getQuantity();  
    private double unitPrice1 = super.getUnitPrice();  

    public void computePrice()  
    { 
        totalPrice1 = quantity1 * unitPrice1 + extraCharge;  
    }  

    public void displayInfo()
    {
        System.out.println("Customer Name : " +  
                    customerName1 + "\nCustomer Number : " +  
                    customerNum1 + "\nQuantity Ordered : " + quantity1 +  
                    "\nUnit Price : $" + unitPrice1  + "\nShipped Price : $"  
                    + extraCharge + "\nTotal Price : $" + totalPrice1);    
    }
}

the main class

import java.util.Scanner;
public class UseOrder
{
    public static void main(String[] args)
    {

        int num, q;
        String name, response;
        double p;
        char responseChar;
        Scanner keyboard = new Scanner(System.in);

        Order order1 = new Order();
        order1.setCustomerName();
        order1.setCustomerNum();
        order1.setQuantity();
        order1.setUnitPrice();
        order1.computePrice();
        order1.displayInfo();

        keyboard.nextLine(); 
        System.out.println("Do you need the shipping and handling service?");
        System.out.println("Enter y or n :");
        response = keyboard.nextLine();
        responseChar = response.charAt(0);
        if(responseChar == 'y')
        {
            ShippedOrder shippedorder1 = new ShippedOrder();
            shippedorder1.getCustomerName();
            shippedorder1.getCustomerNum();
            shippedorder1.getQuantity();
            shippedorder1.getUnitPrice();
            shippedorder1.computePrice();
            shippedorder1.displayInfo();

        }
    }
}

When I run it, this is what the second output comes back as

customer name : null
customer number: 0
Quantity Ordered: 0
Unit Price:0
Shipped Price: $4.0
Total Price: $4.0

[awinston]

You seem to be under the impression that the values of order1's fields are automatically transferred to shippedorder1, but this isn't true.

order1 and shippedorder1 are 2 different objects. You didn't call any of the "setter-methods" for shippedorder1, so all of its fields are going to be the default value of 0 (or 4 in the case of extra charge). Therefore, calling the "getter-methods" for shippedorder1 is going to return those default values. Calling the "getter-methods" of shippedorder1 will not return the values of order1's fields.