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Java Java Objects Delivering the MVP Applying a Discount Code

Posted by Massimo Scola
Massimo Scola
Courses Plus Student 632 Points

normalizeDiscountCode => check for letters or $ --> ??

So we have to check the String whether it contains anything other than a letter or $ sign.

How am I supposed to do that?

Why can't the author gives us a hint how he wants us to solve this problem?

I'm sure the author dosn't want us to try this: https://stackoverflow.com/questions/5238491/check-if-string-contains-only-letters

as this is a supposed to be a beginners course?

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) )
   return this.discountCode = 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"
    }

  }
}

7 Answers

Massimo Scola
PLUS
Massimo Scola
Courses Plus Student 632 Points
Massimo Scola
Massimo Scola
Courses Plus Student 632 Points

if (!Character.isLetter(c) && c!='$'){

that's it

Cristen Hewett
Cristen Hewett
23,811 Points

YES - that's it. thanks

Massimo Scola
PLUS
Massimo Scola
Courses Plus Student 632 Points
Massimo Scola
Massimo Scola
Courses Plus Student 632 Points

I have been "WTF" for quite some time now and I do not know how to proceed.

I have tried this code here

private String normalizeDiscountCode(String discountCode) { this.discountCode = discountCode.toUpperCase(); for (char c : discountCode.toCharArray()) { if (! Character.isLetter(c)) { throw new IllegalArgumentException("Invalid discount code"); } } return this.discountCode; }

So this code checks whether the character is a letter or not. How do I exclude the $ sign?

Lucian Ciopec
Lucian Ciopec
12,778 Points
Lucian Ciopec
Lucian Ciopec
12,778 Points

I did it like this:

if (! Character.isLetter(c) || c!= '$')

It compiles, but now I get the message: Oops! It looks like Task 1 is no longer passing. So i need to figure this out now.

Lucian Ciopec
Lucian Ciopec
12,778 Points
Lucian Ciopec
Lucian Ciopec
12,778 Points

This is my code:

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) {

for(char c : discountCode.toCharArray()) {
  if(! Character.isLetter(c) || c != '$') {
    throw new IllegalArgumentException("Invalid discount code");
  }
}
return discountCode.toUpperCase();

}

}

Lucian Ciopec
Lucian Ciopec
12,778 Points
Lucian Ciopec
Lucian Ciopec
12,778 Points

Maybe I need to add the try catch block in the applyDiscountCode() method

Massimo Scola
PLUS
Massimo Scola
Courses Plus Student 632 Points
Massimo Scola
Massimo Scola
Courses Plus Student 632 Points

I had exactly the same code like yours and it is just frustrating if we can't proceed.

Maybe there is a technique which hasn't been shown in this presentation.

Lucian Ciopec
Lucian Ciopec
12,778 Points
Lucian Ciopec
Lucian Ciopec
12,778 Points

Yes, you're right, thank you!