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Java Java Objects Delivering the MVP Applying a Discount Code

throw new IllegalArgumentException();

I don't understand why this doesn't work.

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) {
    String str = discountCode.toUpperCase();

    char[] charArray = str.toCharArray();

    for (int i = 0; i < charArray.length; i++) {
      char ch = charArray[i];

      if (ch >= 'a' && ch <= 'z' || ch == '$') {
        str = str;
      } else {
        throw new IllegalArgumentException("Invalid discount code");
      }
    }

    return str;
  }
}
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

Steven Parker
Steven Parker
231,122 Points

The string is converted to upper case; but then each character is checked to see if it is between 'a' and 'z' (lower case), which it cannot be at this point.

The test should check for between 'A' and 'Z' instead.