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Java Java Objects Delivering the MVP Applying a Discount Code

David Zhang
David Zhang
946 Points

Can't use regEx here?

I'd finished this challenge using for loop.

However I want to try to use regEx to simplify the code, but it seems my regEx code was somehow wrong. I can't figure it out myself, 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 code) {
    if (!code.matches("/^[a-zA-Z\\$]*$/")) {
      throw new IllegalArgumentException("Invalid discount code");
    }
    return code.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"
    }

  }
}

1 Answer

Brendan Whiting
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

Interesting. It seems like the pattern that it want's shouldn't include the // characters we normally wrap regex with. Maybe that's how regexes work in Java, I dunno.

  private String normalizeDiscountCode(String code) {
    if (!code.matches("^[a-zA-Z\\$]*$")) {
      throw new IllegalArgumentException("Invalid discount code");
    }
    return code.toUpperCase();
  }
David Zhang
David Zhang
946 Points

I just tried whatever the patterns are(even like ^[a-z]*$), there always prompt message "Bummer: java.lang.IllegalArgumentException: Invalid discount code (Look around Order.java line 25)". I don't know what went wrong...

Brendan Whiting
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

Do all those patterns include the // characters? I think that's the problem. Your original pattern worked when I removed the slashes. Basically, code.matches was returning false because there was a problem with the pattern, which then had us enter the if block and threw the exception.

David Zhang
David Zhang
946 Points

Damn, I'd just removed the open and close / sign in my code, and it all worked no matter with or without double escape sign. I will remember this lesson.

David Zhang
David Zhang
946 Points

Thanks for your time and patience. I think my reading needs improving. Lmao that miscommunicating.