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Java Java Objects Delivering the MVP Applying a Discount Code

peterbristow
peterbristow
10,403 Points

Bummer: java.lang.IllegalArgumentException: Invalid discount code (Look arround Oder.java line 26). Whaaat?

Hi

Any idea what I have done wrong here please?

Thanks.

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

public void applyDiscountCode(String discountCode) { this.discountCode = normalizeDiscountCode(discountCode); // *** Line 26 is here. *** }

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;
  }

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

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

  }
}
Ani Azot
Ani Azot
1,754 Points

your 'or' needs to be an 'and'

If letter == '$'

Its value is tested against the condition !Character.isLetter(letter) <the '$' value of letter is NOT a letter>

This returns true as '$' is not a letter

Letter is not tested against the other side of the [or] condition once one side returns 'true' in the case of ||

Since the condition returned true, the statement between the brackets is called - throw new IllegalArgumentException("Invalid discount code");

So you need an && to make sure the other side of the if condition is called and both sides of the condition return true to call the throw new iae statement. This will make sure the value of letter is not a letter AND not a dollar symbol.

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 think! Sorry I'm quite new to Java

1 Answer