Is there a way to make a user only input an int?

[HarleyRowland]

I want to only allow the user to input an int and then if they enter a character which isn't an int i want an error message to appear. How can i do this?

Thanks.

[Zyril]

Hello Harley,

this is very much possible to do. If you specifically want to check if it's an integer I'd suggest that you look into parsing the input and then have a look at the class NumberFormatException.

[pbrockway2]

The only way to make a user enter an int is to apply a screwdriver to their keyboard.

if they enter a character which isn't an int i want an error message to appear

This is a much more realistic design goal.

Assuming we are talking about a console based program...

* Read the input the user enters. (Eg as a character stream, Console, or Scanner. Pick one, or try all three.)
* Convert the input to an int. Scanner has a method that does this for you. Otherwise you convert the String to an int. Oracle's tutorial suggests one way, but I'd go for using the parseInt() method of the Integer class.
* Catch any exception that will occur if what they enters does not convert (ie is not an int).

I hope I haven't confused matters by pointing out so many alternatives. A common approach, these days, seems to be to use a Scanner and its nextInt() method.

[Reddi.Java]

for your problem,we can handle through java script also

like below e.g

function validateForm()
{
var x=document.forms["myForm"]["fname"].value;
if (x==null || x=="")
{
alert("First name must be filled out");
return false;
}
}

The function below checks if a field has been left empty. If the field is blank, an alert box alerts a message, the function returns false, and the form will not be submitted:

now you can try fo your case too.

i think this will help for solve your problem.

regards,
Reddi

[JosAH]

for your problem,we can handle through java script also

I can do it in Lisp, Algol, Fortran, BCPL and more than a dozen other languages; they all don't apply here just as JavaScript doesn't apply.

kind regards,

Jos

[HarleyRowland]

Right, thanks for all your help guys, I'll have a look into some of the methods.

If i'm ever good enough and you guys need help, I'll definite help you! :)

Thank you!