Exception Handling in a while loop

Question

The problem I am having with this code is the following: the variable number can't be a String so I tried to use a try, catch (InputMissmatchException) statement to take care of the issue. However, when in goes in the loop and someone enters a String, the exception is handle but it goes through the loop again using the last valid entry. i.e. I enter 5 and then I enter "hello" the result is: "You must enter a number." but now 5 is counted again.

This makes the counter add one too many to the count variable. And if the user keep using a String, the loop keep adding the last valid entry over and over so the count would be wrong at the end.

Logically speaking I want the program to handle the issue and ask the user to enter a correct entry until an acceptable integer is enter without going through the while loop again; and when the user enters a valid entry, to keep looping or exist (-1).

int number = 0;
int[] count = new int[11];

    try
        {
        number = input.nextInt(); 
        } 
        catch (InputMismatchException y)
        {
        System.out.println("You must enter a number.");
        input.nextLine();

        }    


    while (number != -1)
    {
        try 
        {
            ++count[number];
        } 
        catch (IndexOutOfBoundsException e) 
        {
            System.out.println("Please enter a valid number from the menu.");
        }

        try
        {
        number = input.nextInt();
        } 
        catch (InputMismatchException y)
        {
        System.out.println("You must enter a number.");
        input.nextLine();

        } 
    }

score 1 · Accepted Answer · answered Apr 30 '15 at 00:00

Sounds like you want a while loop until they enter a number

int number = 0;
int[] count = new int[11];

while(true) {
    try
    {
    number = input.nextInt();
    break;
    } 
    catch (InputMismatchException y)
    {
    System.out.println("You must enter a number.");
    input.nextLine();

    }  
}  


while (number != -1)
{
    try 
    {
        ++count[number];
    } 
    catch (IndexOutOfBoundsException e) 
    {
        System.out.println("Please enter a valid number from the menu.");
    }

    while(true) {
        try
        {
            number = input.nextInt();
            break;
        } 
        catch (InputMismatchException y)
        {
            System.out.println("You must enter a number.");
            input.nextLine();
        } 
    }

}

Exception Handling in a while loop

1 Answers1