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Java Java Objects Delivering the MVP Applying a Discount Code

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 :)

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

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!


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

Awesome Steve thanks a lot I understand now :)