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Java Java Objects Delivering the MVP Applying a Discount Code

Joakim Sjöstedt
Joakim Sjöstedt
1,975 Points

Applying a discount code

What am I missing in the normalize method? Compiler says there are errors both with the exception and isLetter... and is the string supposed to be converted to char?

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){
    if(! Character.isLetter(discountCode.toCharArray())) { // || discountCode.toCharArray('$') !=-1){
     throw new illegalArgumentException(discountCode + " 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) {

    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"
    }

  }
}
Daniel Gelabert
Daniel Gelabert
944 Points

I think the main problem is that you are using a char array (discountCode.toCharArray()) as a char, and thats why the compiler crashes. You should use a for structure for each char in the char array, as in this example https://stackoverflow.com/questions/5238491/check-if-string-contains-only-letters

Joakim Sjöstedt
Joakim Sjöstedt
1,975 Points

Hmm, almost there, but still doesn't quite go through: Order.java:13: error: no suitable method found for isLetter(String) if(Character.isLetter(discountCode) || disc =='$') {

private String normalizeDiscountCode(String discountCode){

for(char disc : discountCode.toCharArray()) {

 if(Character.isLetter(discountCode) || disc =='$') {

   return discountCode.toUpperCase(); }

else{

 throw new IllegalArgumentException(discountCode + " invalid discount code");}
    }

}

4 Answers

Daniel Gelabert
Daniel Gelabert
944 Points

Think about it, discountCode is a String, while the method asks for a char Character.isLetter(char).

Joakim Sjöstedt
Joakim Sjöstedt
1,975 Points

OK, so discountCode.charAt(disc)... makes sense :) Thanks :) But now it says that either task 1 is invalid for whatever reason:

private String normalizeDiscountCode(String discountCode)

{

 for(char disc : discountCode.toCharArray()) 

 {

   if(! Character.isLetter(discountCode.charAt(disc)) || disc =='$') 

   {

    throw new IllegalArgumentException(discountCode + " invalid discount code"); 

   }

 }

 return discountCode.toUpperCase();

}

Joakim Sjöstedt
Joakim Sjöstedt
1,975 Points

Oh, and how do I write so that it becomes code here on the forum? Some of the code got converted, and some didn't...

Joakim Sjöstedt
Joakim Sjöstedt
1,975 Points

Still stuck... What do I do if I don't find any help? Task 1 is still the way it was before. Havn't changed it, but compiler says it's not the same...

Daniel Gelabert
Daniel Gelabert
944 Points

I asked the same question a few days ago. Think about it, when there's a '$' the ! Character.isLetter(discountCode.charAt(disc)) is true and goes inside the if code. Check that and you will find the answer. In fact task 1 is still valid, but for some reason the website returns this message.