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Java Java Objects Delivering the MVP Applying a Discount Code

Posted by Jean-Baptiste Orozco
Jean-Baptiste Orozco
1,455 Points

They tell me "It looks like Task 1 is no longer passing." but it should be normal since the check triggers an exception.

Not sure where I made a mistake, to me it's logic that the first task "getting the discount to uppercase" doesn't work anymore since I threw an exception, it should just block the rest of my code.

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;
  }

  private String normalizeDiscountCode(String arg){

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

  public String getDiscountCode() {
    return discountCode;
  }

  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"
    }

  }
}

3 Answers

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

The problem is that your code raises an exception for discount codes that are valid. In fact it actually raises an exception for all discount codes.

You check if a character is not a letter OR not the $ symbol, that means that an exception will be raised if either of those conditions is true. Let's say the character in question was 'A' that is a letter so the first condition would be false, but 'A' is not the $ symbol so the second condition would be true, which means that an exception would be thrown. Even though 'A' is a valid letter for the discount code.

The same type of thing would happen if the character was $, since that is not a letter.

The easiest way around this is to replace OR with AND, that way and exception is only thrown if the character is both not a letter and not the $ symbol. Like this:

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;
  }

  private String normalizeDiscountCode(String arg){

    for (char letter : arg.toCharArray()) {
      if (!Character.isLetter(letter) && letter != '$') { // Replaced || with &&
          throw new IllegalArgumentException ("Invalid discount code");
        }
    }
    arg = arg.toUpperCase();
    return arg;
  }

  public String getDiscountCode() {
    return discountCode;
  }

  public void applyDiscountCode(String discountCode) {
    this.discountCode = normalizeDiscountCode(discountCode);
  }
}
Jean-Baptiste Orozco
Jean-Baptiste Orozco
1,455 Points
Jean-Baptiste Orozco
Jean-Baptiste Orozco
1,455 Points

Aaah ok, thanks for your help

sankalp yadav
sankalp yadav
2,101 Points
sankalp yadav
sankalp yadav
2,101 Points

I was doing the same but it was not passing