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Java Java Objects Delivering the MVP Applying a Discount Code

Zdenek Krcal
Zdenek Krcal
49,910 Points

Please help with JAVA code challenge.

I think my code is correct, but I'm not able to finish this challenge.

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 l : discountCode.toCharArray()) {
      if(! Character.isLetter(l) || l != '$') {
        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"
    }

  }
}
Raphaël Seguin
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Raphaël Seguin
Full Stack JavaScript Techdegree Graduate 29,228 Points

I think your if statement is wrong. The exception should be thrown if the char you're testing is neither a letter nor a $. So the logic should be :

!(Character.isLetter(l) || l = '$' )

2 Answers

andren
andren
28,558 Points

Your code is very close to correct, and the mistake you have made is one I have seem quite a few other students make. This mistake is likely common due to the way the requirement is phrased.

The mistake is that you are checking if the character is not a letter OR not the $ symbol, the way the OR operator works is that if either of the conditions are true if will return true and therefore run the if statement. Let's say the character is in fact a letter, the first condition will be false, but the second condition will return true so the if statement runs and an exception is thrown, even though a letter should not result in an exception. The same is true for the $ symbol, the first condition will be true and therefore the if statement will run even though the second condition is false.

One way around this is to use the && operator instead, that way the if statement will only run if the character is both not a letter and not the $ symbol, which is what the task specifies.

So to sum up, change the || operator in your if statement to && and your code will pass.