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Java Java Objects Delivering the MVP Applying a Discount Code

melissa zhang
melissa zhang
760 Points

where to find out the correct answer?

I couldn't find out which part code is wrong. Could you please help? Do you know anywhere I can check the correct answer. many thanks

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(){
    return discountCode.toUpperCase();
  }

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

Melodie 1
Melodie 1
3,931 Points

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

is missing a paramater of type String , it's supposed to look like this :

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

and here : public void applyDiscountCode(String discountCode) { this.discountCode =discountCode.normalizeDiscountCode(); } you need to pass in the discountCode as an argument to normalizeDiscountCode() , so it should look like this :

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

melissa zhang
melissa zhang
760 Points

Thank you so much. You are a star.

melissa zhang
melissa zhang
760 Points

It seems very confusing that sometimes it needs a parameter in the method sometimes not. Do you know why and when it needs parameter? Thank you.

Melodie 1
Melodie 1
3,931 Points

There is no general rule to that , with time you'll know when you need a parameter and when not, but each time you see an instruction that says " a method x takes something " , that means this method needs a parameter.

melissa zhang
melissa zhang
760 Points

Sorry to bothering you again. I just changed the code as you taught me. But it still shows wrong. Could you please check my new code ? I have just posted another question. I don't know if you can see it. Many thanks.

melissa zhang
melissa zhang
760 Points

I find out what is wrong now. thank you very much.