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Java Java Objects Delivering the MVP Applying a Discount Code

Hitesh Burla
Hitesh Burla
2,552 Points

Throwing Illegal Argument not marking the task as done.

I was asked to throw an illegal argument when a string containing non characters or $ symbol is given as discount. I've done the required but it's not working.

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;
  }

  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 String getItemName() {
    return itemName;
  }

  public int getPriceInCents() {
    return priceInCents;
  }

  public String getDiscountCode() {
    return discountCode;
  }

  public void applyDiscountCode(String discountCode) {
    String normalizedDiscountCode;
    normalizedDiscountCode = normalizeDiscountCode(discountCode);
    this.discountCode = normalizedDiscountCode;
  }
}
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"
    }

  }
}
Hitesh Burla
Hitesh Burla
2,552 Points

try { for(char letter: discountCode.toCharArray() ) { if(!Character.isLetter(letter) || letter !='$') { throw new IllegalArgumentException("Invalid discount code"); } } } catch(IllegalArgumentException iae) { System.out.printf("%s", iae.getMessage()); }

Even when I've updated this...it doesn't work!

Hitesh Burla
Hitesh Burla
2,552 Points

Looks like the problem is with by if condition... when I changed it to if(!Character.isLetter(letter) && letter !='$'). It solved the issue.

1 Answer

Christian Damsgaard
Christian Damsgaard
4,239 Points

What you need to do is to change is the || in your if statement, to &&. By doing this you changes the statement from saying, "if one of the following statements is true, then throw the illegal argument", to "if both of these statements is true, then throw the illegal argument".

So change from:

  private String normalizeDiscountCode(String discountCode) {

      for(char letter: discountCode.toCharArray() ) {
       if(!Character.isLetter(letter) || letter !='$') {
         throw new IllegalArgumentException("Invalid discount code");
       }
      }
    return discountCode.toUpperCase(); 
  }

To:

  private String normalizeDiscountCode(String discountCode) {

      for(char letter: discountCode.toCharArray() ) {
       if(!Character.isLetter(letter) && letter !='$') {
         throw new IllegalArgumentException("Invalid discount code");
       }
      }
    return discountCode.toUpperCase(); 
  }

That should do the trick.