import javax.swing.*;

public class LeapYear 
{
    public static void main( String[] args )
    {
        String input;
        int year;
        boolean done = false;
        
        //keep executing this until we're done (user cancels)
        while( !done )
        {
            //get the input from the user
            input = JOptionPane.showInputDialog( "Enter a year:" );
            
            if( input != null )
            {
                year = Integer.parseInt( input ); //need to parse the user input as an integer
                
                //first, check if it's a leap year. For it to be a leap year, 
                //it needs to either be divisible by 4 and NOT by 100, or be divisible by 400
                if ( ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0) )
                {
                    JOptionPane.showMessageDialog( null, year + " is a leap year! :)", 
                        "Leap Year!", JOptionPane.INFORMATION_MESSAGE );
                }
                else //it is not a leap year
                {
                    JOptionPane.showMessageDialog( null, year + " is not a leap year. :(", 
                        "No Leap Year", JOptionPane.INFORMATION_MESSAGE );
                }
            }
            else //the user canceled
            {
                done = true;
            }
        }
    }
}