[RESOLVED] Help with JOptionPane

[Drazzminius]

I'm in the US Marines and stationed in Japan. I'm taking an online Java Programming class (part of my degree curriculum) and am only in week 2. I have the following task:

Write a Java program that reads an integer and checks whether it is even.

If your input is 25, your output should be:

Is 25 even?

false

If your input is 2000, your output should be:

Is 2000 even?

true

Also, the program must check if the number the user entered is between 1 and 1000.

If your input is 25, your output should be:

The number 25 between 1 and 1000 is true.

If your input is 2000, your output should be:

The number 2000 between 1 and 1000 is false.

1.The input and output must use JOptionPane dialog and display boxes.

My code thus far is:

import javax.swing.JOptionPane;

public class NumberChecker {
   public static void main (String args[]) {
      // Prompt the user to enter a number
     String numberString = JOptionPane.showInputDialog(null, "Enter a number:", "Number Checker", JOptionPane.QUESTION_MESSAGE);
		
     //  Convert the string into an int value
     int number = Integer.parseInt(numberString);
				
     //  Check if the number is even
     int isEven; { 
     number = number % 2;
		
     //  Display the result in a message dialog box declaring if it is even or odd
     JOptionPane.showMessageDialog(null, "Is " + number + " an even number?\n> " + isEven, "Number Checker", JOptionPane.INFORMATION_MESSAGE);}
	}
     //  Check if the number is in the prescribed range
     boolean isRange; {  
     return ! ((1 < number) && (number < 1000)); 
			
     // Display the result in a message dialog box declaring if it falls in the prescribed range
     JOptionPane.showMessageDialog(null, "Is the number " + number + " between 1 and 1000?\n> " + isRange, "Range Checker", JOptionPane.INFORMATION_MESSAGE);}
     {
     System.exit (0);
     }
}

My problem is that when I go to compile, I'm receiving errors for the return ! and an error code for my range checker saying that it is looking for a symbol. Can anyone tell me what I'm doing wrong and why?

Thank you in advance!

[Drazzminius]

I downloaded JCreator LE and am trying to clean it up a little.

Here's what I've gotten so far:

import javax.swing.JOptionPane;

public class NumberChecker {
	public static void main (String args[]) {
		// Prompt the user to enter a number
		String numberString = JOptionPane.showInputDialog(null, "Enter a number:", "Number Checker", JOptionPane.QUESTION_MESSAGE);

		//  Convert the string into an int value
		int number = Integer.parseInt(numberString);
		int number = range;

		//  Check if the number is even
		int isEven; {
		number = number % 2;

		//  Display the result in a message dialog box declaring if it is even or odd
		JOptionPane.showMessageDialog(null, "Is " + number + " an even number?\n> " + isEven, "Number Checker", JOptionPane.INFORMATION_MESSAGE);}
	}
		//  Check if the number is in the prescribed range
		boolean isRange; {
			return ! ((1 < range) && (range < 1000));

		// Display the result in a message dialog box declaring if it falls in the prescribed range
		JOptionPane.showMessageDialog(null, "Is the number " + range + " between 1 and 1000?\n> " + isRange, "Range Checker", JOptionPane.INFORMATION_MESSAGE);}
		{
		System.exit (0);
	}
}

Still getting the errors, however.

[kfcSmitty]

Uhh, I would recommend you go through a basic Java tutorial because this is all wonky.

You're not declaring your methods properly and you also don't have any error catching.

Here is a quick example of what you need to do. There are much better ways to do this, but here are the basics.

  try{
		   
	      // Prompt the user to enter a number
	     String numberString = JOptionPane.showInputDialog(null, "Enter a number:", "Number Checker", JOptionPane.QUESTION_MESSAGE);
			
	     //  Convert the string into an int value
	     int number = Integer.parseInt(numberString);
					
	     //  Check if the number is even
	     int checkEven = number % 2;
	     
	     boolean isEven = false;
	     
	     if (checkEven == 0)
	     	isEven = true;
	     
	     boolean inRange = false;
	     if (number < 1000 && number > 1)
	    	 inRange = true;
			
	     //  Display the result in a message dialog box declaring if it is even or odd
	     JOptionPane.showMessageDialog(null, "Is " + number + " an even number?\n> " + isEven, "Number Checker", JOptionPane.INFORMATION_MESSAGE);
	   	 JOptionPane.showMessageDialog(null, "Is the number " + number + " between 1 and 1000?\n> " + inRange, "Range Checker", JOptionPane.INFORMATION_MESSAGE);
	   	 
		   }catch(NumberFormatException ne){
			   JOptionPane.showMessageDialog(null, "You must enter an integer.", "Number Format Error", JOptionPane.ERROR_MESSAGE);
		   }catch (Exception e){
			   JOptionPane.showMessageDialog(null, "An Unknown error has occured.","Unknown Error", JOptionPane.ERROR_MESSAGE);
		   }//end try/catch

[Drazzminius]

The class I'm enrolled in is an Intro to Java, so I guess it's basically a tutorial. The book (JAVA: How to Program 7th ed) presents the material in basic syntax that is run from the command line and has input/output there also. The instructor presented a couple of very basic dialog box examples, but the context is a little outside my reasoning so far.

I really appreciate your help. I wasn't aware of the the "checkEven" command and that alone makes a world of difference. I pasted what you presented into my original in JCreator and am still getting a few errors with the error checking that you provided; I'll have to iron that out. I'm sure it's probably declarations on my part again.

Thank you again and have a great day!

[kfcSmitty]

Glad to help, but 1 thing: checkEven is a variable, not a method.

Since you were using input %(mod) 2, if it was even it would return 0. So if it was 0, I was telling the program that the number was even.