Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Java Java Objects Delivering the MVP Applying a Discount Code

Talal Alghamdi
Talal Alghamdi
1,603 Points

How to verify a specific character?

I verified the letters, but couldn't figure out how to verify the $ character.

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 code, char ignore) {

                              for (char ch: code.toCharArray()){ 
                                if  ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))  {

                                discountCode= code.toUpperCase();
                              } 

                              else {
                              throw new IllegalArgumentException("Invalid discoubt code");  
                              }
                              }
                              return discountCode;  
                              }

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"
    }

  }
}

1 Answer

andren
andren
28,538 Points

You might have been overthinking the solution a bit, the answer is actually very simple. To check that the character is equal to $ you can simply use a normal equal comparison ch == '$'. If you add it together with another || like this:

if  ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || ch == '$')  {
    discountCode= code.toUpperCase();
} 

Then your if statement will be correct.

Though I see that you have added an ignore parameter to your normalizeDiscountCode method. You have to remove that in order to complete the challenge, since that is not meant to be there.

It is also worth mentioning that while the above if statement works it can be greatly simplified using a method on the Character class called isLetter. As the name implies isLetter checks if the argument provided is a letter or not. By using that in place of the comparisons you wrote before you get this:

if  (Character.isLetter(ch) || ch == '$')  {
    discountCode= code.toUpperCase();
} 

Which is easier to read and performs the same task.