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Java Java Objects Delivering the MVP Applying a Discount Code

ubaldo sanchez
ubaldo sanchez
3,149 Points
Posted by ubaldo sanchez
ubaldo sanchez
3,149 Points

I am not able to get past the illegal argument exception

Im not sure if the program is prematurely exiting before the text case captures the illegal exception or if im not doing it right.

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){

    if ( !discountCode.matches ("[a-zA-Z]+")||! discountCode.contains("$")){
      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"
    }

  }
}

2 Answers

andren
andren
28,558 Points
andren
andren
28,558 Points

There is a logic issue with the condition of your if check. As it is written it will mark valid discount codes like "abc" as invalid. This is because your code checks if the discount code does not contain a letter or does not contain $, that means discounts codes will only be accepted if they contain both letters and the $ symbol, a discount code only containing letters or only containing the $ symbol will not pass, even though they would be valid codes.

Your condition can be fixed pretty simply though, instead of having two conditions just include both of your criteria in your regex. Doing so is as simple as including the $ symbol at the end of the expression like this:

private String normalizeDiscountCode (String discountCode){
  if (!discountCode.matches("[a-zA-Z$]+")){
    throw new IllegalArgumentException("Invalid discount code.");
  }
  return discountCode.toUpperCase();
}

That will make the regex check for both letters and the $ symbol, if any symbol other than those are found in the code an exception will be raised, exactly as intended.

Valentino Galasso
Valentino Galasso
1,488 Points

Why is needed the "+" at the end of expression "[a-zA-Z$]+"?

ubaldo sanchez
ubaldo sanchez
3,149 Points
ubaldo sanchez
ubaldo sanchez
3,149 Points

That was exactly it. Thank you!