I have these two methods which I cant quite figure out the best way to go about their algorithm. I am writing a program that acts like a restaurant menu and collects user order.
The implementation is,
welcome user and present him with the menu
while the user has not entered 'q', send the user input to a method called getGoodOrderLine(String str)
this method will then check the input for the following,
- First, it must check that a number is present before trying to read it; if there is no number, the entry is an error unless it starts with ‘q’ or ‘Q’, which tells the program to quit.
- then, determine which item the user is asking for by looking at just the first letter. So an input “2 Hello” means 2 hamburgers. the assumption is that if there is a digit in the string, the digit appears before the word, for simplicity
- finally, if the first letter is not (H,C,F or D), print an error message and ask that it be re-entered.
My problem is that, I created a while loop that should loop until the user input is valid, but it doesn't seem to be working, here is my code:
import java.util.*;
public class MenuApp
{
//global variables
public static double HAM = 3.75;
public static double CHEESE = 4.10;
public static double FRIES = 2.50;
public static double DRINKS = 1.75;
public static void main(String [] args)
{
//variables
String order;
double total = 0.0;
boolean stopLoop;
//print welcome message && collect order
welcomeCustomer();
order = collectItem();
order = getGoodOrderLine(order);
stopLoop = order.equalsIgnoreCase("q");
while(!stopLoop)//while user hasnt typed q
{
if(order.equalsIgnoreCase("q"))
{
break;
}
order = getGoodOrderLine(order);
//will add the value of user order to total here if order is valid
//leave loop if useer inputs q
}
//ending program
Date today = new Date();
System.out.println("Date: " + today);
System.out.println("Please pay " + total + "\n");
System.out.println("End of processing");
}
public static void welcomeCustomer()
{
System.out.println("Welcome to QuickieBurger!");
System.out.println("Hamburgers \t\t $" + HAM);
System.out.println("cheeseBurgers\t\t $" + CHEESE);
System.out.println("Fries\t\t\t $" + FRIES);
System.out.println("Drinks\t\t\t $" + DRINKS+"\n");
}
public static String collectItem()
{
String userInput = null;
Scanner kbd = new Scanner(System.in);
System.out.println("Please place your order (e.g., 3 ham). Enter Q to quit.");
userInput = kbd.nextLine();
System.out.println(userInput);
return userInput;
}
public static String getGoodOrderLine(String userInput)
{
String result = "";
boolean pass = false;
if(userInput.equalsIgnoreCase("q"))
{
return userInput;//early exit, return q
}
//check if it has at least a digit first
for(char c: userInput.toCharArray())
{
if(Character.isDigit(c))
{pass = true;}
}
//if it doesn't have a digit || string doesnt begin with a digit
if(!Character.isDigit(userInput.charAt(0)))
{
if(!pass)
System.out.println("Your entry "+ userInput + " should specify a quantity");
else
System.out.println("Your entry "+ userInput + " does not begin with a number");
}
else
{
//do the remaining tests here
}
return result;
}
}
I keep getting null pointer and index out of bounds exceptions when testing for Character.isDigit(userInput.charAt(0));
the problem is you are returning empty string so charAt(0) give error since char array has no elements.and if you want to collect items you need to use a collection type like list and u can't use a array since array has fixed length.and to get price of user input product you need to map prices with product names .so u can use map.but i used 2 arrays which act as a map.check this and it's output.
import java.util.ArrayList;
import java.util.List;
import java.util.Date;
import java.util.Scanner;
public class myMenu {
public static String names[] = {"HAM", "CHEESE", "FRIES", "DRINKS"};
public static double prices[] = {3.75, 4.10, 2.50, 1.75};
public static ArrayList<List<String>> allitems = new ArrayList<>();
static double total = 0.0;
public static void main(String[] args) {
welcomeCustomer();
collectItem();
}
public static void welcomeCustomer() {
System.out.println("Welcome to QuickieBurger!");
for (int i = 0; i < names.length; i++) {
System.out.println(names[i] + "\t\t\t" + prices[i]);
}
}
public static void collectItem() {
String userInput = "";
Scanner kbd = new Scanner(System.in);
System.out.println("Please place your order (e.g., 3 ham). Enter Q to quit.");
userInput = kbd.nextLine();
while (!getGoodOrderLine(userInput)) {
userInput = kbd.nextLine();
}
}
private static boolean getGoodOrderLine(String userInput) {
if (userInput.equalsIgnoreCase("q")) {
transaction();
} else if (!Character.isDigit(userInput.charAt(0))) {
System.out.println("quesntity should be specified. try again");
return false;
} else {
for (int i = 0; i < names.length; i++) {
String items = names[i];
//get the first charactor from userinput
char c = 0;
for(int z=0;z<userInput.length();z++){
c=userInput.charAt(z);
if(Character.isAlphabetic(c)){
break;
}
}
if (Character.toLowerCase(items.charAt(0)) ==Character.toLowerCase(c)) {
String s="";
int x=0;
while(Character.isDigit(userInput.charAt(x))){
s+=userInput.charAt(x);
x++;
}
int quentity=Integer.parseInt(s);
double pri = prices[i];
double sub = quentity * pri;
total += sub;
ArrayList<String> subitem = new ArrayList<>();
subitem.add(items);
subitem.add(String.valueOf(quentity));
subitem.add(String.valueOf(sub));
allitems.add(subitem);
return false;
}
}
System.out.println("this not a valid food item.try again");
}
return false;
}
private static void transaction() {
//ending program
Date today = new Date();
System.out.println("-------------------------------------");
System.out.println("Date: " + today);
for (List<String> menu : allitems) {
System.out.println(menu.get(0)+" "+menu.get(1)+" = "+menu.get(2));
}
System.out.println("Please pay " + total + "\n");
System.out.println("------------------------------------");
System.out.println("End of processing");
}
}
output>>
Welcome to QuickieBurger!
HAM 3.75
CHEESE 4.1
FRIES 2.5
DRINKS 1.75
Please place your order (e.g., 3 ham). Enter Q to quit.
2 Hello
4 CHEESE
q
-------------------------------------
Date: Sun Nov 02 02:59:56 PST 2014
HAM 2 = 7.5
CHEESE 4 = 16.4
Please pay 23.9
------------------------------------
End of processing