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Java Java Objects Delivering the MVP Applying a Discount Code

Posted by Will Anderson
Will Anderson
28,683 Points

Hmmm...I ran order.applyDiscountCode("h1!") and I expected it to throw an IllegalArgumentException, but it didn't.

I spent half a day getting to step 2, and now I'm rather stuck. Is the test condition something that isn't quite called out in the requirements during the course? It appears that there are 2 error conditions in the test data, why didn't it stop after the first one? Or am I reading that oddly as well?

Did see Craig's note (from 18 days ago) that there will be a change to the instructions ...

Thanks for any help!

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) {
    try {
    this.discountCode = normalizeDiscountCode(discountCode);
    } catch (IllegalArgumentException iae) {
      System.out.println(iae.getMessage());  
    }
  }
}
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

Your normalizeDiscountCode method is actually completely fine, the issue is with how you call it in the applyDiscountCode method. In task 1 you were simply instructed to call the method, you were not told to add a try...catch block to deal with the exception it might produce. And that is the issue, the fact that you are catching the IllegalArgumentException exception on your own.

As the error message states, when it runs your code to verify that it works it expects that some tests will result in an IllegalArgumentException reaching the challenge tester, but they never do. And that is because that exception is being caught by your own code before it has a chance to be reach it.

If you remove the try...catch block from your own code 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;
  }

  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);
  }
}

Then your code will pass the challenge.

Will Anderson
Will Anderson
28,683 Points
Will Anderson
Will Anderson
28,683 Points

Andren hit it right on the 'money spot'. I commented out the try/catch and passed the challenge. Seems I 'mis-overstimated' the instructions, and was too aggressive in finding exceptions that one would like the end user to never see. I'll have to settle with the grief that I was 'too correct'. ;-) Thanks Andren!