How to use canceled button in JOptionPane

[mike ryan]

Hi,

I am using JOptionPane to get an int value for a switch statement, but i can't figure out how i can see if someone clicks the "cancel" option.
I looked in the API for it but i still can't figure it out!

Here is the snippet where i need to use it

public static void main(String[] args) {

        int input = 0;
        double inputD = 0;
        boolean weiter = true;
        int choice = 0;

        while (weiter == true) {
            try {

                choice = Integer
                        .parseInt(JOptionPane.showInputDialog("1: get quadrat for an integer\n2: Get quadrat for a double\n"
                                        + "3:get the square root of an integer\n4: exit program"));//what can i use here if cancel is clicked?

            }

            catch (NumberFormatException e) {

                System.out.println("Please enter a valid integer");
                continue;

any help would be greatly appreciated.

Thanks
Mike

[Ralph Cook]

Doing a quick web search, it appears that clicking "Cancel" causes the input dialog to return null instead of a String. You'll have to get the string returned by the dialog and test it for null to do what you want. It might be a good idea anyway, just in case the user types "two", so you can control the error message he gets and try again.

rc

[mike ryan]

Hi Ralph,

I have read that also in the API and other sources, but my problem is that i am using "choice = Integer.ParseInt" if i were just using JOptionPane and looking for a string then it is simple to see if the input is null.
Or do i need to write an extra method just to use the cancel button?


Mike

[mike ryan]

Hi again,

OK i got it fixed ;) thanks for the tipp Ralph it got me thinking in the right direction!

Here is how i fixed it for a reference for anyone else having this problem.

public static void main(String[] args) {

        int input = 0;
        double inputD = 0;
        boolean weiter = true;
        int choice = 0;
        String choice1 ="";

        while (weiter == true) {
            try {

                choice1 = JOptionPane.showInputDialog("1: get quadrat for an integer\n2: Get quadrat for a double\n"
                                        + "3:get the square root of an integer\n4: exit program");//what can i use here if cancel is clicked?            
            
            
            if(choice1 == null ){
                System.out.println("ok works");
                System.exit(0);
            }
            else{
                choice = Integer.parseInt(choice1);
                weiter = true;
            }
            }
            

            catch (NumberFormatException e) {

                System.out.println("Please enter a valid integer");
                continue;

            }
           

            switch (choice) {

Mike

[Campbell Ritchie]

What about one of the other kinds of dialog for JOptionPane? Or you can pass YES_NO_OPTION, or YES_NO_CANCEL_OPTION. There should be something in the Java™ Tutorials.

[mike ryan]

Campbell Ritchie wrote:What about one of the other kinds of dialog for JOptionPane? Or you can pass YES_NO_OPTION, or YES_NO_CANCEL_OPTION. There should be something in the Java™ Tutorials.

Thanks Campbell, I know there are other JOptionPane methods and will check those out as well in time. My last posted code works fine now and the reason i wanted to fix that as is was is
because i had the entire program written already and then thought i should utilize the cancel button too although i had a case method to quit the program.



Mike