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

Posted by benyoungblood
benyoungblood
10,062 Points

Issues with method to normalize String.

I'm not entirely sure what to even ask here. In the lesson we are working with a method that returns a char. The method in this exercise returns a String. I've gone to Oracle's website and I have tried to find resources. I thought the following would give me what I want because I am testing if it is not a unicode character or if it is not containing a $ symbol, then we will throw the exception. 

if (! discountCode.charAt() || ! discountCode.contains('$') {
     throw new IllegalArgumentException("blah blah");
}

Again I don't really know what to even ask.

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

  private String normalizeDiscountCode(String discountCode) {
    if (! discountCode.charAt() || ! discountCode.contains('$')) {
      throw new IllegalArgumentException("Invalid discount code.");
    }
    return discountCode.toUpperCase();
  }

  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"
    }

  }
}

1 Answer

Fatemah Tavakoli
Fatemah Tavakoli
13,797 Points
Fatemah Tavakoli
Fatemah Tavakoli
13,797 Points

Hi,

The question is asking to loop through the discountCode and make sure that there are only letters or '$' character. the problem comes with "discountCode.charAt()". Java String charAt() method returns the character at the specified index, which is not asked by the question. To solve it we should turn our discountCode string Into array of char and check if it meets the conditions. To get this array we use ".ToCharArray()" method. 

private String normalizeDiscountCode(String discountCode) {
    //looping through the array
    for (char codeChar:discountCode.toCharArray()){
      //checking the conditions
      if ( !Character.isLetter(codeChar) && codeChar != '$'){
        throw new IllegalArgumentException("Invalid discount code"); 
      }
    }
    return discountCode.toUpperCase(); 
  }

Hope it helps! :)

benyoungblood
benyoungblood
10,062 Points

Thank you!