Java Error Check

[Rahim2312]

I have a JOptionPane that displays and asks the user to input a number. I only want this input to accept ODD numbers. How would I check to make sure that the number entered is ODD only? I have no idea even where to begin on this one?!

[Diargg]

Where do you want the validation to occur? While they type? When they hit enter?

First, we have to know if a number is odd. How do you know if a number is odd?

Second, how do you get input from a JOptionPane?

Third, how do you use that input? What kind of checks would you perform on it to see if it's odd?

[Rahim2312]

I want the validation to occur once the user hits enter.

To check if a number is odd (I THINK....) I could use

if (var1 % 2 != 0)
//Then the number is odd

The way I was going to get input from a JOption Pane was going to be:

var1= Integer.valueOf(JOptionPane.showInputDialog("Enter an odd number"));

If the number is not odd, I want display an error message (I know I would use a do-while loop for this), if the number is odd, I want to pass var1 to a different module, and continue with the code.

[Diargg]

Sounds like you have everything you need. What's the issue then?

[Rahim2312]

My java compiler doesn't like the "%" sign?

[Diargg]

Post your code. Use code tags.

[Rahim2312]

This is the statement I am working with (or trying to make work)

	{
	String var1;
	
		do{var1 = Integer.valueOf(JOptionPane.showInputDialog("Enter an odd number"));
			if (var1 % 2 == 0){
				JOptionPane.showMessageDialog(null, "Please enter an odd number!");
				}else{
					Advance(var1);
			}
			}while (var1 % 2 != 0);
    }

[Diargg]

Are you sure var1 is an integer? What's the remainder of a String?

[Rahim2312]

I could be totally wrong in saying this, but I thought that input into the JOptionPane had to be input as a string and then converted to what type you actually needed it

[Diargg]

	{
	String var1;
		var1 = Integer.valueOf(JOptionPane.showInputDialog("Enter an odd number"));

You're converting from a String to an int to a String again. Declare var1 as an int.

Your input is a String - "Enter an odd number"
Your output is also a String, which you've converted to an int. You need to store it in an int as well.

[Rahim2312]

Ah Hah! One more issue I am running into...with the code from my post 7. If an even number is entered, it is giving me the message to "Enter an odd number" like it should, but then it is leaving the program, I want it to loop back up and ask me to again input an odd number.

[Diargg]

}while (var1 % 2 != 0);

Does this say "do the above while var1 is even"? Or does it say "Do the above while var1 is odd"?

[Rahim2312]

It says to do the above code while var1 is odd. Which means I should flip it to read:

var1 % 2 == 0

[Diargg]

What is the error case? Should it repeat the question if var1 is odd?

[Rahim2312]

Switching the symbol like below fixed it. If the number was odd, it should have carried on to Advance. Changing the code to:

var1 %2 == 0

has it functioning as needed.

Thank you for your time and support.