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Java Java Objects Delivering the MVP Applying a Discount Code

Lucian Vrabiescu
Lucian Vrabiescu
735 Points
Posted by Lucian Vrabiescu
Lucian Vrabiescu
735 Points

Why doesn't it work

I've commented some code becouse I'm not sure if it's right, either way it doesn't work and I dont know why

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;
  }

  public void applyDiscountCode(String discountCode) {
   // try {
      discountCode = normalizeDiscountCode(discountCode);
   // } catch (IllegalArgumentException iae) {
      //System.out.printf("%s. Please try again. %n",
       //                   iae.getMessage());
    //}
      this.discountCode = discountCode;
  }
  private String normalizeDiscountCode(String discountCode){
    discountCode = discountCode.toUpperCase();
    boolean validCode = true;
    for (char c : dicountCode.toCharArray()) {
      if (! c.isLetter() && c != '$') {
        throw new IllegalArgumentException("Invalid discount code");
      }
    }
    if (validCode) {
      return discountCode;
    }
  }
}

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi Lucian,

You've pretty much got that right. However, you want to throw the error if c is not a letter AND is not a '$'.

At the moment, using ||, if you pass in a '$' as c, the error will get thrown because !Character.isLetter('$') evaluates to true and you only need one side of the || to evaluate to true for the error to be thrown.

Check your comparison logic. :wink:

Steve.

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi there,

Your applyDiscountCode method looks OK but you can shorten it a little:

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

Now, in your normalizeDiscountCode method, you have validCode which never changes, and is unnecessary. You've done most of the code that's required. Start with the for loop then, once that's completed, return the uppercase code. You'll need to spell discountCode correctly in there too :wink:.

Also, isLetter() is a class method of Character; you can't call it on c. Try Character.isLetter(c) instead.

Remove the if test; it isn't needed. That should work fine.

Let me know how you get on.

Steve.

Lucian Vrabiescu
Lucian Vrabiescu
735 Points
Lucian Vrabiescu
Lucian Vrabiescu
735 Points

Hi Steve!

I followed your tips and it still doesn't work, what's the problem?

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

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

  public void applyDiscountCode(String discountCode) {
   this.discountCode = normalizeDiscountCode(discountCode);
  }
  }
  private String normalizeDiscountCode(String discountCode){
    for (char c : discountCode.toCharArray()) {
      if (! Character.isLetter(c) || c != '$') {
        throw new IllegalArgumentException("Invalid discount code");
      }
    }
      return discountCode.toUpperCase();
  }
}

Thanks for your help!

Luci.