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Java Java Objects Delivering the MVP Applying a Discount Code

Xuanzheng Lin
Xuanzheng Lin
2,466 Points
Posted by Xuanzheng Lin
Xuanzheng Lin
2,466 Points

Code is failing

No idea why the code just failed lol.

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

  // cut out class code for brevity - srh

  public void applyDiscountCode(String discountCode) {
    String want;
    try {
      want = normalizeDiscountCode(discountCode);
      this.discountCode = want;
    } catch (IllegalArgumentException iae) {
      System.out.print(iae.getMessage());
    }
  }

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

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

Say we have a character 'a'. That is NOT '$'. So, an OR would throw the error as a != '$' evaluates to true. Using an OR we only need one side to be true for the error to be thrown.

Send in a '1' and this is not a letter so !isLetter('1') is true (not-false) and 1 != '$' is also true. So, comparing with && will pick this up and throw the error. That's correct.

Same with '$'. It's not a letter so !isLetter('$') is true and '$' != '$' is false. Again, this would evaluate to true with an OR which would throw the error, when it shouldn't.

Make sense?

Steve.

my head hurts now!

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

Hi there,

You've got some extra code in there that's not needed. You don't need the try/catch block to pass this challenge.

In the normalizeDiscountCode method, you've correctly used a for:in loop to iterate over the code, converted to a char array. You've not done the comparison correctly, though. I think you need && not ||.

You can also tidy up your returned value by omitting the extra variable. Just return the string with .toUpperCase() applied directly to it: 

  private String normalizeDiscountCode(String discountCode){
    for (char letter : discountCode.toCharArray()) {
      if (!Character.isLetter(letter) && letter != '$') {
        throw new IllegalArgumentException("Invalid discount code.");
      }
    }
    return discountCode.toUpperCase(); 
  }

I hope that helps,

Steve.

Xuanzheng Lin
Xuanzheng Lin
2,466 Points
Xuanzheng Lin
Xuanzheng Lin
2,466 Points

Thanks bro. U r totally right. But can u explain u need && instead of ||?