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

Jacob Copeland
Jacob Copeland
1,473 Points

How do I phrase the condition for the if-statement when trying to throw this exception?

I'm not sure how to say "the string doesn't contain anything other than a letter or '$'".

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) {
    if (/*discountCode.indexOf('$') != -1 || ?????????*/) {
      throw new IllegalArgumentException("Invalid discount code");
    }
    this.discountCode = discountCode.toUpperCase();
    return this.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

Jean Malan
Jean Malan
10,781 Points

Where you have the $ sign, put - ([^a-zA-Z] +'$' )

Implementing [^a-zA-Z] is basically asking the to see if there is anything that isn't a letter and therefore throws yours iae. We, of course, add in the $ sign because we still want that.

Jacob Copeland
Jacob Copeland
1,473 Points

It didn't compile :(

./Order.java:24: error: illegal start of expression if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ ./Order.java:24: error: ')' expected if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ ./Order.java:24: error: not a statement if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ ./Order.java:24: error: ';' expected if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ ./Order.java:24: error: cannot find symbol if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ symbol: variable a location: class Order ./Order.java:24: error: cannot find symbol if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ symbol: variable zA location: class Order ./Order.java:24: error: cannot find symbol if (discountCode.indexOf([^a-zA-Z] + '$') != -1) { ^ symbol: variable Z location: class Order Note: JavaTester.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 7 errors