Java Java Objects Delivering the MVP Applying a Discount Code

Cordell Hayes
Cordell Hayes
3,502 Points

Get correct answer but fails test.

Hi team,

This test asks me to throw an exception if string contains non letters. I have completed this task, the preview shows the correct message but i still "fail" the test. Any ideas 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 String getItemName() {
    return itemName;
  }

  public int getPriceInCents() {
    return priceInCents;
  }

  public String getDiscountCode() {
    return discountCode;
  }

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

  private String normalizeDiscountCode (String discountCode)
  {
    char[] dicountCodeArray = discountCode.toCharArray();
    for (char item : dicountCodeArray)
    {
      if (!Character.isLetter(item) || item != '$')
          {
            throw new IllegalArgumentException ("Invalid discount code");
          }
    }
    return discountCode.toUpperCase();
  }
}
Example.java
public class Example {

  public static void main(String[] args) {
    // This is here just for example use cases.

    Order order = new Order(
            "Yoda PEZ Dispenser",
            600);

    // These are valid.  They are letters and the $ character only
    order.applyDiscountCode("abc");
    order.getDiscountCode(); // ABC

    order.applyDiscountCode("$ale");
    order.getDiscountCode(); // $ALE


    try {
      // This will throw an exception because it contains numbers
      order.applyDiscountCode("ABC123");
    } catch (IllegalArgumentException iae) {
      System.out.println(iae.getMessage());  // Prints "Invalid discount code"
    }
    try {
      // This will throw as well, because it contains a symbol.
      order.applyDiscountCode("w@w");
    }catch (IllegalArgumentException iae) {
      System.out.println(iae.getMessage());  // Prints "Invalid discount code"
    }

  }
}

1 Answer

Tonnie Fanadez
Tonnie Fanadez
UX Design Techdegree Graduate 22,767 Points

Hello Cordell Hayes .

I like how you approached this challenge, the code was spot on! just a minor adjustment.

Instead of using the pipe operator || you should use the ampersand operator && .

This is because for the exception to be thrown it has to meet both conditions i.e. is not a letter AND is not equal to $ . When you use OR operator, it creates a loophole e.g. if the code is $AbCD ; the loop will first encounter the dollar symbol and will automatically trigger the exception throwing. The loop won't even bother checking the second condition after OR since the first condition has tested true; it just moves on. But when you use the AND operator you force the looping code to check whether the second condition is also met before executing the rest of the code.

See my adjusted code below, hope it will help:

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

Cheers man...