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Java Java Objects Delivering the MVP Applying a Discount Code

Joe Tran
Joe Tran
4,768 Points

Can't pass through the compile error

when i try to check my work, it keeps saying that a compile error happens at != in line 8, does anyone know the error?

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

  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 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) {
    try {
          this.discountCode = normalizeDiscountCode(discountCode);  
         } catch (IllegalArgumentException iae) {
                 System.out.println(iae.getMessage());
         }
   }
}
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

Cam Richardson
seal-mask
MOD
.a{fill-rule:evenodd;}techdegree
Cam Richardson
Front End Web Development Treehouse Moderator 16,895 Points

The error is this:

./Order.java:8: error: incomparable types: char and String
      if (!Character.isLetter(letter) && (letter != "$")) {

Which means that you are trying to compare letter (a char) and "$" (a string). This is because in Java (and C# I believe) you must denote a character literal with single quotes like this:

char letter = 'A';

If you don't do this, the compiler will think you're meaning to define a String literal even if the string is a single character. Give it a try and let me know if that helps! :)

Joe Tran
Joe Tran
4,768 Points

Thx Richarson!

I have changed it to single quote and it compiled successfully!

However, I bumped into a new error:

Bummer: Hmmm...I ran order.applyDiscountCode("h1!") and I expected it to throw an IllegalArgumentException, but it didn't

Why cant the code throw the error in this h1! example.... any help?

Joe Tran
Joe Tran
4,768 Points

Oops, i find out the reason.

It is because the question has not asked me to catch the exception....