How to make the switch statement more accurate?

Question

We were ask to make a program using the switch statement..

Here is my code:

    double price = 0, totalPrice;

    System.out.print("Enter the number of your choice: ");
    int optionNumber = Integer.parseInt(kb.readLine());

    switch(optionNumber)
    {
        case 1:
            price = 190.00;
            break;
        case 2:
            price = 410.00;
            break;
        default:
            System.out.println("ERROR: Invalid number!");
            break;
    }

    System.out.print("Enter quantity: ");
    int quantity = Integer.parseInt(kb.readLine());

    totalPrice = price * quantity;

So basically, the user will input a certain number and it will have different prices... inside the switch statements. but if the user inputs a wrong number, it will display an error message and i dont want the user to enter the quantity which will be executed after the switch statement. we are not allowed to use any methods or functions and i dont want to code repeatedly like this:

    System.out.print("Enter the number of your choice: ");
    int optionNumber = Integer.parseInt(kb.readLine());

    switch(optionNumber)
    {
        case 1:
            price = 190.00;
            System.out.print("Enter quantity: ");
            int quantity = Integer.parseInt(kb.readLine());
            totalPrice = price * quantity;
            System.out.print("Total price: " + totalPrice);
            break;
        case 2:
            price = 410.00;
            System.out.print("Enter quantity: ");
            int quantity = Integer.parseInt(kb.readLine());
            totalPrice = price * quantity;
            System.out.print("Total price: " + totalPrice);
            break;
        default:
            System.out.println("ERROR: Invalid number!");
            break;
    }

is there any other way not to use if else, methods, functions or coding repeatedly? ANY HELP WILL BE APPRECIATED.

when you say you don't want code "repeatedly" does that mean no loops? — chancea, Jan 20 '15 at 13:52
You can never know, the OP doesn't want to use methods for some reason so it wouldn't surprise me if loops are out of the question also — chancea, Jan 20 '15 at 13:56
another reasonable solution is to throw an exception in the default case — Adriaan Koster, Jan 20 '15 at 13:57
Do you want to: (a) repeatedly ask for input until the user get's it right; (b) not ask for a quantity and then move on; or (c) exit the program entirely? You probably need to define your specification more clearly for your question in order to get good answers. — Andy Brown, Jan 20 '15 at 14:02

score 1 · Answer 1 · answered Jan 20 '15 at 13:51

1

Use as this:

while(!valid option)
   //do this stuff

Use a flag and set it to true if the number entered is valid, so it will go to your next instruction; else ask again for input.

answered Jan 20 '15 at 13:51

z21

129
6

score 1 · Accepted Answer · answered Jan 20 '15 at 13:57

You can use a boolean flag and make it false if invalid option is selected.
Then only ask user further if flag is true.

    System.out.print("Enter the number of your choice: ");
    int optionNumber = Integer.parseInt(kb.readLine());
    boolean flag = true;
    switch (optionNumber) {
        case 1:
            price = 190.00;
            break;
        case 2:
            price = 410.00;
            break;
        default:
            flag = false;
            System.out.println("ERROR: Invalid number!");
            break;
    }
    if (flag) {
        System.out.print("Enter quantity: ");
        int quantity = Integer.parseInt(kb.readLine());
        totalPrice = price * quantity;
        System.out.print("Total price: " + totalPrice);
    }

Howard Renollet · Answer 3 · 2015-01-20T14:01:33.077

0

You could just remove default from the switch statement and check to see if the price is equal to 0 after the switch statement

double price = 0, totalPrice;

System.out.print("Enter the number of your choice: ");
int optionNumber = Integer.parseInt(kb.readLine());

switch(optionNumber)
{
    case 1:
        price = 190.00;
        break;
    case 2:
        price = 410.00;
        break;
}

if (price == 0)
{
     System.out.println("ERROR: Invalid number!");
}
else
{
    System.out.print("Enter quantity: ");
    int quantity = Integer.parseInt(kb.readLine());
    totalPrice = price * quantity;
    System.out.print("Total price: " + totalPrice);
}

This keeps you from adding unnecessary variables (like a boolean flag) when you already have one (price) with a default value of 0 that you can check against.

edited Jan 20 '15 at 14:01

answered Jan 20 '15 at 13:56

Howard Renollet

4,609
1
24
31

Quoting the OP: _is there any other way not to use if else [...]_, `if else` is not an option (don't know why tough) – Narmer Jan 20 '15 at 14:01
@Narmer I think he's talking about using `if/else` statements repeatedly, like inside every `case`. That's how I understood the question anyway. I would think a single `if/else` statement would be ok the way I read the question. *"is there any other way not to use if else, methods, functions or coding **repeatedly***? " – Howard Renollet Jan 20 '15 at 14:03
I think that _repeatedly_ refers to _coding_ (as in _i dont want to code repeatedly like this_ written above that). This doesn't leave out the fact that the OP isn't completely clear on what she wants to do. – Narmer Jan 20 '15 at 14:08
1

Well, the accepted answer dissipates all the doubts :D – Narmer Jan 20 '15 at 14:10

score 0 · Answer 4 · edited May 23 '17 at 12:12

0

Throw an exception

  default:
            throw new InvalidArgumentException("Invalid number!");

See also InvalidArgumentException vs UnexpectedValueException

edited May 23 '17 at 12:12

Community

1
1

answered Jan 20 '15 at 13:56

blank

17,852
20
105
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How to make the switch statement more accurate?

4 Answers4