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Java Java Objects Delivering the MVP Applying a Discount Code

Haris Sheikh
PLUS
Haris Sheikh
Courses Plus Student 1,288 Points

Hey can anyone tell me where I am messing up on this code? To upper case.

I keep getting an error. I am lost at why this is happening

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

  private String normalizeDiscountCode (String discountCode)
  {
    discountCode.toUpperCase();
    return 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 String applyDiscountCode(String discountCode) 
  {
    discountCode = normalizeDiscountCode(discountCode);
    this.discountCode = discountCode;
    return 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

Hi, In your method

private String normalizeDiscountCode (String discountCode) { discountCode.toUpperCase(); return discountCode; }

you should return discountCode.toUpperCase() instead discountCode. The original string discountCode isn't changed after toUpperCase() because Strings in Java are immutable so all operations on the string return a new copy.

private String normalizeDiscountCode (String discountCode) { return discountCode.toUpperCase(); }

Caleb Kemp
Caleb Kemp
12,755 Points

I didn't see your answer when I clicked to answer it, otherwise I wouldn't have, your answer is perfectly correct.

Caleb Kemp
Caleb Kemp
12,755 Points

Okay, so your error is a fairly simple one. In the normalizeDiscountCode method, you correctly call the toUpperCase method, however, you do not save the changes. Therefore, when the value is returned, it is still lower cased.

solution:

this in normalize method

discountCode.toUpperCase();
    return discountCode;

should become this

return discountCode.toUpperCase();

where the value is immediately returned and does not need to be saved OR this

String value = discountCode.toUpperCase();
return value;

hope it helps