CS302 Fall 2012 Exam 2 Solution

// Part I: Write a complete program 
import java.util.Scanner;
public class DairyDelivery {
  public static void main(String[] args) {

    final double MILK_PRICE      = 2.75;
    final double BOTTLE_DEPOSIT  = 1.50;
    final int MIN_ORDER = 3;
    final double DISC1 = 10.0;     // DISCOUNT LEVELS
    final double DISC2 = 20.0; 
    final double DELIVERY  = 2.5;  // $ 0- 9.99 is $2.50
    final double DELIVERY1 = 1.5;  // $10-19.99 is $1.50
    final double DELIVERY2 = 0;    // $20+      is $0.00
    Scanner stdin = new Scanner(System.in);
    int halfgals = -1, bottles = -1;

    // Get number of bottles ordered
    while ( halfgals < MIN_ORDER ) {
      System.out.print("Number of half gallons? ");
      halfgals = stdin.nextInt();
      if (halfgals < MIN_ORDER) {
        System.out.println(
          "Error! Please enter an int >= "+MIN_ORDER);
      }
    }
    // Get number of empty bottles returned
    while ( bottles < 0 ) {
      System.out.print("Number of bottles returned? ");
      bottles = stdin.nextInt();
      if ( bottles < 0 ) {
        System.out.println(
          "Error! Please enter an int >= 0");
      }
    }
    // Compute invoice items
    double milk     = halfgals * MILK_PRICE;
    double deposit  = halfgals * BOTTLE_DEPOSIT;
    double refund   = bottles  * BOTTLE_DEPOSIT;
    double delivery = 2.50;                         // delivery chg is $2.50
    if ( milk >= DISC2 )      delivery = DELIVERY2; // if >= 20, chg is FREE
    else if ( milk >= DISC1 ) delivery = DELIVERY1; // else if >= 20, chg is $1.50
    double ppg = (milk + delivery) / (halfgals / 2.0); // price per gallon
    System.out.println(
      "Milk Subtotal:           $" + milk + "\n" +
      "Bottle Deposit Charge: +  " + deposit + "\n" +
      "Bottle Return Refund:  -  " + refund + "\n" +
      "Delivery Charge:       +  " + delivery + "\n" + 
      "Total Bill:            = $" + (milk+deposit-refund+delivery) + "\n" +
      "Cost Per Gallon:       = $" + ppg + "/gal" );
  } // end main
  
} // end class