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Java Java Objects Delivering the MVP Applying a Discount Code

Posted by Joshua Graham
Joshua Graham
9,882 Points

I've been stuck on this for a while, I've tried using the matches method and contains method

is there method I don't know about or am I just misusing these?

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;
  }

  public void applyDiscountCode(String discountCode) {

    this.discountCode = normalizeDiscountCode(discountCode);

  }
  private String normalizeDiscountCode(String discountCode){

    if(discountCode.contains("[!-#0-9%-~]+")){

         throw new IllegalArgumentException("Invalid discount code");

    }

    return discountCode.toUpperCase();
  }


}
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"
    }

  }
}

1 Answer

Christopher Augg
Christopher Augg
21,223 Points
Christopher Augg
Christopher Augg
21,223 Points

Joshua,

You are close man.

The videos for this part of the course are teaching the use of Character.isLetter(char c) for testing. One way to solve this challenge is to loop through a String.toCharArray() and test that each character is a '$' (c == '$') or (||) a letter (Character.isLetter(c)) using the aforementioned method. However, you can use regex to solve it as well. Java Strings have regex built in and the method you are looking for is String.matches("regex"). 

    private String normalizeDiscountCode(String discountCode) {

        if(!discountCode.matches("[(A-Za-z)|($)]+")) {
          throw new IllegalArgumentException("Invalid discount code.");
        }
        return discountCode.toUpperCase();
    }

Chris

Joshua Graham
Joshua Graham
9,882 Points

yeah I eventually gave up on using matches or contains and ended writing another method that used a loop and isLetter which worked.