Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Objects Delivering the MVP Applying a Discount Code

Carlo Antonio Bilbao
Carlo Antonio Bilbao
24,113 Points

Can not write code to throw exception for strings containing $.

I've written code to not throw an exception when the discount code contains letters but not when it contains "$"

Order.java
public class Order {
  private String itemName;
  private int priceInCents;
  private String discountCode;

  private String normalizeDiscountCode(String discountCode) {
    for (char letter : discountCode.toCharArray()) {
      if (! Character.isLetter(letter)) {
        throw new IllegalArgumentException("Invalid discount code.%n");
      }
    }
    this.discountCode = discountCode.toUpperCase();
    return this.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);
  }
}
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

Try this, it's much simpler:

private String normalizeDiscountCode(String discountCode) {
    if discountCode.contains("$") {
        throw new IllegalArgumentException("Invalid discount code.%n");
    }
    return discountCode.toUppercase();
}

All it's doing is it takes in a argument and in the argument contains "$" then raise an error. If all goes well, just return the uppercased version of the argument.

I hope this helps. ~Alex

Carlo Antonio Bilbao
Carlo Antonio Bilbao
24,113 Points

I actually want the to pass a discount code that contains an $ rather then create an exception for it. Basically I want to throw and exception for any other symbol other than $

Alex Bratkovskij
Alex Bratkovskij
5,329 Points

Hello Carlo,

Now at the current stage it looks OK, now we're missing jsut one small detail. IF (discountCode does not consist of letters OR discountCode doesnt start with '$' we will throw an exception at users.

Do u need help with code itself, or whats stopping you from writing a code?

-Alex