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Java Java Objects Delivering the MVP Applying a Discount Code

Saad Hamid
Saad Hamid
3,150 Points
Posted by Saad Hamid
Saad Hamid
3,150 Points

Not Able to complete the challenge Exercise

I am having trouble in completing task 2 of Apply Discount code exercise

I have written method for "normalized" method, which throws an error that task 1 is not passing

I am not able to figure out what's wrong with the code

Can anyone please help?

private String  normalizeDiscountCode (String discountCode)
  {
   discountCode = discountCode.toUpperCase();

    for(char charArr : discountCode.toCharArray()){
     if((!Character.isLetter(charArr)) && (!discountCode.contains("$"))) 
        {
      throw new IllegalArgumentException("Invalid Discount Code"); 
     }
    }

    return discountCode;
  }



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

  private String  normalizeDiscountCode (String discountCode)
  {
   discountCode = discountCode.toUpperCase();

    for(char charArr : discountCode.toCharArray()){
     if((!Character.isLetter(charArr)) && (!discountCode.contains("$"))) 
        {
      throw new IllegalArgumentException("Invalid Discount Code"); 
     }
    }

    return discountCode;
  }

  public int getPriceInCents() {
    return priceInCents;
  }

  public String getDiscountCode() {
    return discountCode;
  }

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

3 Answers

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Saad,

You're pretty close with that. However, you want to test each letter within the for loop. Having a blanket contains for the whole string removes that specificity that you need.

Your first test is correct, the second should simply check if the character does not equal '$'.

My code looks like:

  private String normalizeDiscountCode(String code){
    for(char letter : code.toCharArray()){
      if(!Character.isLetter(letter) && letter != '$'){
        throw new IllegalArgumentException("Invalid discount code");
      }
    }

    return code.toUpperCase();
  }

I hope that helps.

Steve.

Steve Hunter
Steve Hunter
57,712 Points

The test fires the code "$@ving$" at your code, for example - there are other tests behind the scenes.

Let's work your logical tests:

if((!Character.isLetter(charArr)) && (!discountCode.contains("$")))

So, let's use the @ symbol which is what the test is expecting to fail. The first test is isLetter which will return false which is then negated to true.

The second test contains("$") will return true, negated to false. The && has a true and a false so it won't throw the exception.

Testing for:

if(!Character.isLetter(letter) && letter != '$')

First test @ isn't a letter; negated to true. The second test is also true as '@' is not equal to '$'. Two true evaluations means the exception gets thrown.

Steve.

Houssem Mhimdi
Houssem Mhimdi
664 Points

Did you tested this ??

Steve Hunter
Steve Hunter
57,712 Points

Yeah - it ran fine for me. Did it not work for you?

Houssem Mhimdi
Houssem Mhimdi
664 Points

Yes i just tested it right now, it works im still gravitated more to the matches() method instead ...

Steve Hunter
Steve Hunter
57,712 Points

I might agree if this were a real-world problem but it isn't. I'm aware of the course content and what's been taught so far. The challenges are designed to reiterate the content of the previous videos which helps reinforce that content and help with learning.

Regular expressions haven't been taught yet at this point of the Java track, so I'm keeping 'on message' supporting Saad by adhering to course content rather than introducing something that's totally new inside a forum post. There's lots of ways of solving many of the challenges - many are much more elegant code-wise but that's not what the challenges are about. By reinforcing the video content, we help Treehouse students learn by repetition and reinforcement.

:+1: :smile:

Houssem Mhimdi
Houssem Mhimdi
664 Points

totally agree on this.

Houssem Mhimdi
Houssem Mhimdi
664 Points
Houssem Mhimdi
Houssem Mhimdi
664 Points

@Saad Hamid You have to use matches() instead to verify that you voucher contains only characters and ignore the other special characters but allow $.... so instead use this: 

if( !Character.isLetter(charArr) &&  !discountCode.matches("[a-zA-Z$]+") )
Saad Hamid
Saad Hamid
3,150 Points
Saad Hamid
Saad Hamid
3,150 Points

Thank you Houssem Mhimdi and Steve Hunter for your help. I am able to get through my problem with your solution.

Steve Hunter
Steve Hunter
57,712 Points

No problem! Glad you got it fixed. Shout if you run into any more problems! :+1:

Steve :smile: