Should I use IndexOf List in this case?

[tangara goh]

Dave Tolls wrote:That last bit of your code (the bit where you are trying to find the pet and whether it is sold) should be a call to the method Carey showed.

public ResponseEntity<Order> placeOrder(@RequestBody Order order) {
    if (isSold(order.getPetId()) {
         throw new ResponseStatusException(HttpStatus.BAD_Request, "pet is sold already, order can't be created");
    }
// Process order
}

Of course that new method ought to be in a service layer rather than in the controller, but small steps...

Hi Dave,

Someone just told me that I should check if the order is null before I do the checking on the petId,

So, is it ok if I just add a && condition to state petId is null and with the above, then I throw a ResponseStatusException?

I have also refactored the code to use a Service layer but my brain is not working cos when I started with this base line to check if the order is null, then I do not know what to return ?

public Order placeOrder(Order order)
if ( order == null){
then ? return what ? null or break or ???

Could you advise me ? tks.

[Carey Brown]

When faced with this kind of  decision, one where throwing an Exception is a possible choice, think to yourself, "is this an exceptional state?"  That is, during any sort of normal running of the program could this ever occur unless there's a programming bug, a hicup in some dependent service, or perhaps, bad user input that wasn't dealt with properly? Could this state be dealt with right here and now in this method or do we need to shrug our shoulders and pass the error back up the calling chain to be dealt with? Should execution continue on or is the state such that continuing would cause further problems?

If you look at your null Order problem against these questions it should be somewhat obvious as to your course of action.