Why isn't this working?

Question

For Java Objects task 2 of 2 isn't passing...

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 capitalizeCode) {
    char[] chars = capitalizeCode.toCharArray();

    for (char c : chars) {
      if ( !Character.isLetter(c) && capitalizeCode.indexOf('$') == -1 ) {
        throw new IllegalArgumentException("Invalid discount code.");
      }
    }
    return capitalizeCode.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"
    }

  }
}

Answer 1 · 2017-04-03T03:17:30Z

April 3, 2017 3:17am

The problem point is around these lines of code:

for (char c : chars) {
      if ( !Character.isLetter(c) && capitalizeCode.indexOf('$') == -1 ) {
        throw new IllegalArgumentException("Invalid discount code.");
      }
    }

So from their error screen we have the example "$@ving$". Now lets walk through this

char c = '$' (a valid character) '$' is not a valid character(so true) And index of '$' will equal to 0 because that is its first location in the array. So in this case we don't throw the exception (true && true) =true So move on to the next char in the array.

char c = '@' (not a valid character) '@' is not a valid character(so true) and index of '$' will be equal to 0 because that its first location(Ah! Here is our problem) (true && true) = true but we should have (true && false) and throw our exception.

So the problem is the use of capitalizeCode.indexOf('$') == -1 as this will always return a number greater than -1 if it contains a single $ in the String. So IllegalArgumentException will never be thrown.

To fix this we simply update the logic to consider each character on its own.

 for (char c : chars) {
      if ( !Character.isLetter(c) && c != '$' ) {
        throw new IllegalArgumentException("Invalid discount code.");
      }
    }

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Tyler Furby

Tyler Furby

Why isn't this working?

1 Answer

Todd Seabrook

Todd Seabrook