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Java Java Objects Delivering the MVP Applying a Discount Code

Posted by James Kane
.a{fill-rule:evenodd;}techdegree
James Kane
Front End Web Development Techdegree Student 3,070 Points

I feel like I made this more complicated than it needed to be but it was the only solution I could think of, help plz

I think this would work as a method but obviously its not what Craig is looking for, any help much appreciated :)

Order.java 
public class Order {
  private String itemName;
  private int priceInCents;
  private String discountCode;

  public Order(String itemName, int priceInCents) {
    this.itemName = itemName;
    this.priceInCents = priceInCents;
  }

  private String normalizeDiscountCode(String discountCode) {
    return discountCode.toUpperCase();
    for (int i = 0; i < discountCode.length(); i++) {
      char validationCheck  = discountCode.charAt(i);

      if (validationCheck != "[A-Z]") || (validationCheck != "[$]") {
        throw new IllegalArgumentException("Invalid discount code");
      }
    }
  }

  }
// snipped for brevity

  public void applyDiscountCode(String discountCode) {
    this.discountCode = normalizeDiscountCode(discountCode);
  }
}

1 Answer

Steve Hunter
Steve Hunter
57,712 Points

Hi James,

Firstly, you are immediately returning out of the normalizeDiscountCode method so most of your code won't be reached. Move the return to the bottom of the method; it should be the last line.

After doing that you get a load of errors with your comparisons. Let's break down a different way of iterating over a string. We can use a method called toCharArray() which converts your string to an array of chars. We can then use a for:in loop to pull out each character in turn. It would look like this:

    for(char letter : discountCode.toCharArray()){
      // do some stuff with each letter
    }

So, now we have each letter isolated in turn and stored in the local variable, letter. We want, first, to see if it is a letter. There's a method, it's a class method, on the Character class called isLetter(). No prizes for guessing what it does! It returns true or false depending on what is passed in, i.e. is the parameter a letter. It's a class method so we call it on Character, chained with dot notation, and pass in the letter variable like this: Character.isLetter(letter).

We also need to test if letter is/isn't a dollar sign. We need to consider the logic carefully, here. We want to throw an exception if the character is NOT a letter AND is NOT a dollar sign. So we need to negate the isLetter test with a preceding !, and also test, with != if the character is not '$'. That needs joining with an AND, &&. If both those conditions are met, hence the &&, throw the exception.

That could look like:

    for(char letter : discountCode.toCharArray()){
      if(!Character.isLetter(letter) && letter != '$'){
        // throw the exception & message here
      }
    }

That's it - if the code execution has made it this far, return the uppercase version of discountCode.

I'll leave you to put all that together - let me know how you get on!

Steve.

Steve Hunter
Steve Hunter
57,712 Points

P.S. Make sure you return the uppercase discountCode outside the loop and before the end of the method.

James Kane
.a{fill-rule:evenodd;}techdegree
James Kane
Front End Web Development Techdegree Student 3,070 Points

Awesome Steve thanks a lot I understand now :)

Steve Hunter
Steve Hunter
57,712 Points

:+1: