Question

Okay, first off I am very, very new to java. For this project I need to design a program that takes a product number, an amoutn sold, calculates the total, and then displays it. However, I need to to display when I select option 2, which is a seperate private class, to be honest I don’t even know where to begin. Any help would be appreciated.

import java.util.Scanner;

public class Attempt1
{
//method to pause until a key is pressed
public static void pause() 
{ 
    try 
    { 
        System.out.print("Press <Enter> to continue..."); 
        System.in.read(); 
    } 
    catch (Exception e)
    {
        System.err.printf("Error %s%c\n",e.getMessage(),7);
    }
}//end pause

public static void main(String[] args)
{
    //variables to capture keyboard input
    Scanner keyBd = new Scanner( System.in );
    char selection;
    //int selection;

    do{//display menu
        System.out.println("\n--------------");
        System.out.println("Retail Sales\n");
        System.out.println("1. Enter Products Sold");
        System.out.println("2. Display Total Retail Sales");
        System.out.println("3. Exit\n");
        System.out.print  ("Selection: ");

        //get menu selection
        selection = keyBd.next().charAt(0);
        //selection = keyBd.nextInt();

        //process menu selection
        switch (selection){
            case '1':
                enterProducts();
                break;
            case '2':
                displaySales();
                break;
            case '3':               
                //recognize as valid selection but do nothing
                break;
            default :
                //System.out.printf("%c\n",7);
                System.out.println("Invalid Selection");
        }//end switch

    }while( selection != '3');

}//end main()

private static void enterProducts()
{
    Scanner inp = new Scanner(System.in);

    int product,quantity;
    double total = 0.00;

    System.out.print("Enter product #(1-5)(0 to stop): ");
    product=inp.nextInt();

    while(product !=0)
        {
        System.out.print("Enter quantity: ");
        quantity=inp.nextInt();
    switch( product ){
    case 1:total+=quantity*2.98;
    break;
    case 2:total+=quantity*4.50;
    break;
    case 3:total+=quantity*3.98;
    break;
    case 4:total+=quantity*4.49;
    break;
    case 5:total+=quantity*6.87;
    break;
    default:System.out.println("Invalid Product Number");
    System.out.println("Product Number Does not Exist");

    if(product<0 && product>=6)
      {
    System.out.print("Enter product #(1-5)(0 to stop): ");
    product=inp.nextInt();
    System.out.print("Enter quantity: ");
    quantity=inp.nextInt();
      }
    break;
    }
    System.out.print("Enter product #(1-5)(0 to stop): ");
    product=inp.nextInt(); 
    }

    pause();    
    }
private static void displaySales()
{
    System.out.println( "The total retail value was: " + total );
    pause();    
}

}//end MenuDemo

Answer 1

Here is an algorithm for improving your code:

1. At the beginning of your your main add a variable total and initialize it with 0: double total=0;
2. Change the enterProducts method’s return type to double: private static double enterProducts() and return the local variable total at the end from this method after the call to pause: return total;
3. In the case for the input of 1 add the returned value from enterProducts to the current value of total (it’s the total inside your main): total += enterProducts();
4. Add to the method displaySales an double argument: private static void displaySales(double total) and change the call to it in the main’s case for 2 to displaySales(total);