Java Exception

[Darr2cool78]

Hello! For my university assignment I had to create a prog**ram that calculated the n**th Line of pa**scals tria**ngle (inputed by user) and display the cont**ents of that line, and I have done so...my problem now is that I would like to make my program a bit cooler by making it throw and expcetion if an int is not entered, but I dont know how to do it correctly, this is my working program (sorry for the ***s but i dont want classmates to google my work )

[Fou-Lu]

That explains the *'s >.<
Exception handling in Java is very easy, just gets some getting used to. Scanner's nextInt call will throw a NoSuchElementException, IllegalStateException or InputMismatchException.
What you want is not to toss an exception, rather to catch it. This is done quite simply with:

PHP Code:

int number = 0;
try
{
    number = sc.nextInt();
}
catch (Exception ex)
{
    System.out.println("Invalid entry!");
} 


Combine that with a do/while loop and some flushing:

PHP Code:

boolean isGood = false;
int number;
do
{
    try
    {
        System.out.print("Enter Required Line Number: ");
        number = sc.nextInt();
        isGood = true;
    }
    catch (Exception ex)
    {
        System.out.println("Invalid entry!");
        sc.nextLine();
    }
} while (!isGood);
// Process it. 


[Darr2cool78]

Thanks very much for the help much appreciated, I was wondering how this code fits into my program, I guess i thought i knew how to place it but everytime i try i get errors or It just doesnt see the exception

[Fou-Lu]

It should replace most of your main.

[Darr2cool78]

When i put it in like this it keeps telling me number is already declared in the main, damn im not the coder i thot i was i cant place this, im bad with exceptions

[Fou-Lu]

That means you have an int number specified more than once. I moved my declaration above the do/while since there really isn't a need to keep instantiating it.
Don't forget to declare your scanner, I'd also put that outside of the loop.

[Darr2cool78]

Originally Posted by Fou-Lu

That means you have an int number specified more than once. I moved my declaration above the do/while since there really isn't a need to keep instantiating it.
Don't forget to declare your scanner, I'd also put that outside of the loop.

Well I finallly got it working, Thanks so much for your help
(hope u dont mind but i removed my original code incase classmates are on snooping as today is handin day)