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Start your free trialRay Green
4,690 PointsillegalArgumentExceptions
Is my code incorrect or is the treehouse code challenge thing malfunctioning? When i run this the compiler literally prints my IllegalArgumentException which is the whole purpose of the challenge but its getting passed as incorrect.
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 letter : discountCode.toCharArray()){
if (! Character.isLetter(letter) || letter != '$'){
throw new IllegalArgumentException("Invalid discount code.");
}
}
discountCode = discountCode.toUpperCase();
return discountCode;
}
}
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(); // $ALE
try {
// This will throw an exception because it contains numbers
order.applyDiscountCode("ABC123");
} catch (IllegalArgumentException iae) {
System.out.println(iae.getMessage()); // Prints "Invalid discount code"
}
try {
// This will throw as well, because it contains a symbol.
order.applyDiscountCode("w@w");
}catch (IllegalArgumentException iae) {
System.out.println(iae.getMessage()); // Prints "Invalid discount code"
}
}
}
2 Answers
Yanuar Prakoso
15,196 PointsHi Ray
You almost finish the challenge. You just make a small mistake here:
for(char letter : discountCode.toCharArray()){
if (! Character.isLetter(letter) || letter != '$'){ <-- this part is wrong
throw new IllegalArgumentException("Invalid discount code.");
}
}
the challenge said if the discountCode characters is NOT(a letter OR '$') then throw new IllegalArgumentException. Thus you should write the code as if(!(Character.isLetter(letter) || leter == '$')) like this:
for(char letter : discountCode.toCharArray()){
if (! (Character.isLetter(letter) || letter == '$')){
throw new IllegalArgumentException("Invalid discount code.");
}
}
or if you still want to use negation for each statement, you must transform it into: if(!Character.isLetter(letter) && letter != '$') like this:
for(char letter : discountCode.toCharArray()){
if (! Character.isLetter(letter) && letter != '$'){
throw new IllegalArgumentException("Invalid discount code.");
}
}
This is what is known as De Morgan's Law, you can read more about it here
I hope this can help a little
Jennifer Nordell
Treehouse TeacherHi there! You're doing great, but the logic in your character comparison is a bit off. You're saying if it's not a letter or it's not a dollar sign then throw an exception. So, for instance, if I sent in the letter "h" here, it would throw an exception, because it's not equal to the dollar sign. Remember, with an or, ||
only one must be true for the following block to execute. And since "h" is not equal to a dollar sign, the exception will be thrown.
What we want here is the neither/nor logic and this needs an and with &&
. We're saying if it's not a letter and it's not a dollar sign, then throw the exception.
Long story short, switching out your ||
for &&
causes this to pass.
Hope this helps!