INvalid input exception

Question

I have a menu which reads integers for input ,here is the method for the menu:

public int menu(String _menuHeader,String[] _menuItems) throws InvalidInputException {
    int choice = 0;
    do {
        try {
            scanner.nextLine();
            System.out.println(_menuHeader);

            for (int i = 0; i < _menuItems.length; i++) {
                System.out.println(" " + (i + 1) + " " + _menuItems[i]);
            }

            choice = scanner.nextInt();

            if (choice <= 0 || choice > _menuItems.length) {
                throw new InvalidInputException();
            }
        } catch (Exception e) {
            System.out.println("Enter valid input");
            validInput = false;
        } catch (InvalidInputException e) {
            System.out.println("Please enter a choice between 1 and" + _menuItems.length);
            validInput = false;
        }
    } while (!validInput);
}

Now I want to catch a exception when the input is out of bound of the allowed choices, i.e input 7 for choices 1 and 2,

For this I have tried using InvalidInputException, but this gives a an compile error as 'cannot find symbol InvalidInoutException' although I have imported 'import.java.Throwable/Exception;'

is it not? I just search it on the java docs ,maybe I don't know how to read on java docs, what should I be importing then? — Snedden27
– Snedden27, Commented Oct 4, 2013 at 20:32
Do you have a link to the docs? The / in the import is very unconventional. — pamphlet
– pamphlet, Commented Oct 4, 2013 at 20:36
There is a typo in your code: +_menuItems.lenght should read +_menuItems.length... — aschipfl
– aschipfl, Commented Jun 22, 2016 at 17:55

Community · Accepted Answer · 2017-05-23 10:34:05Z

4

Do you have a custom exception class defined for your "InvalidInputException"?. If not please go through this post for creating custom exception classes.

How to define custom exception class in Java, the easiest way?

edited May 23, 2017 at 10:34

CommunityBot

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answered Oct 4, 2013 at 20:32

Gireesh

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1 Comment

Snedden27 Over a year ago

thanks didn't knew we have to define our custom class

Georgian · Accepted Answer · 2013-10-04 20:34:23Z

4

There is not such thing as InvalidInputException in java.lang. You will have to create your own custom exception, and name it as you wish.

Sorry to say this, but judging from your code you have poor knowledge of how the exception handling works in Java. If this is exception practice, then refactor your code accordingly. If not, don't use exceptions at all. You don't need them in this snippet of code.

answered Oct 4, 2013 at 20:34

Georgian

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Comments

Mike Housky · Accepted Answer · 2013-10-04 20:39:21Z

I didn't look up the import, but the problem is that you catch Exception before InvalidInputException. Java uses the first matching catch to handle an exception, so if you catch a superclass in front of any of its subclasses, the subclass catches will never occur.

Reverse the order of your catches and you'll have better luck.

Edit: OK, I did look it up and Scanner.nextInt() doesn't throw that exception anyway. You probably want java.util.InputMismatchException, but check for yourself:

http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#nextInt%28%29

PS: This really isn't the best way to handle invalid input, by the way. The Scanner class has a hasNextInt() method to detect whether a valid integer is next in the input stream or not. As a rule, it's generally better to avoid throwing and catching exceptions if there's a sensible alternative. The Scanner hasNext* methods are specifically designed to give you those sensible alternatives.

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