CODEWITHSUNDEEP
javawhile-loopnumberformatexception
Ty Givens
Ty Givens

Reputation: 111

While Loop issue (Java)

I'm trying to make a while loop that prompts the user to re-enter data if they use an invalid entry. In my program I'm asking the user to input a number(0-3), so if they enter anything other than that I want an error message to pop up, asking them to re-enter their data. I don't know what I'm doing wrong in my loop. No matter what I enter I always get the error message.

String itemChoice = JOptionPane.showInputDialog(null, itemList);
    itemChoiceNum = Integer.parseInt(itemChoice);

    //test to make sure the input is valid
    while (itemChoiceNum != 0 || itemChoiceNum != 1 || itemChoiceNum != 2 || itemChoiceNum != 3) {
        JOptionPane.showMessageDialog(null, "Sorry that's not a valid choice. Please start again.");
        itemChoice = JOptionPane.showInputDialog(null, itemList);
    }

NumberFormatException

    while (itemChoiceNum != 0 && itemChoiceNum != 1 && itemChoiceNum != 2 && itemChoiceNum != 3) {
        try {
            JOptionPane.showMessageDialog(null, "Sorry that's not a valid choice. Please start again.");
                                        itemChoice = JOptionPane.showInputDialog(null, itemList);
                                        itemChoiceNum = Integer.parseInt(itemChoice);
        }

        catch (NumberFormatException itemChoiceNum ) {
            JOptionPane.showMessageDialog(null, "Sorry that's not a valid choice. Please start again.");
        }

Error

Exception in thread "main" java.lang.NumberFormatException: For input string: "f"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:492)
    at java.lang.Integer.parseInt(Integer.java:527)
    at VendingClass.displayVend(VendingClass.java:82)
    at VendingMachineDemo.main(VendingMachineDemo.java:12)

Upvotes: 1

Views: 199

Answers (2)

Suresh Atta
Suresh Atta

Reputation: 121998

Use should && instead || in the while condition.As of now it always returns True.

Upvotes: 1

rgettman
rgettman

Reputation: 178263

Your logic is incorrect. It's always true that the choice isn't 0 or it isn't 1 or it isn't 2; you want "and" with the && operator.

while (itemChoiceNum != 0 && itemChoiceNum != 1 && itemChoiceNum != 2 && itemChoiceNum != 4) {

Upvotes: 6

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