Help on assignment, don't understand JOptionPane and showInputDialog

Question

Hi, I am currently studying java and have problems doing my assignment. here is the assignment question. What I am looking for is pointers and hints to start on my assignment. I am not looking for the source code, rather the way to actually understand it and start writting my code
I believe this assignment wanted me to create a class Object called Zeller with the methods in it and a ZellerTester to test the Object?
I read up on the JOptionPane and the showInputDialog, but don't really quite understand it.
Do i need a constructor for the Object Zeller?
Does my assignment require me to put the showInputDialog as a method in the Zeller class? Or put it in the ZellerTester?
The isLeapYear is a method in the Object Zeller?
Here is the assignment question
Examine the method
showInputDialog() and study its function. Note the return type of this method.
Write a program on the following requirements:
1. Use the JOptionPane facility to ask the user for three positive integers,
representing the day, month and year of a date.
2. Use the Zeller�s congruence formula to find the day of the week.
3. Should include a method boolean isLeapYear(int year)
that will return true if year is a leap year, and false otherwise.
The method should check for leap years as follow:
return true if the year is divisible by 400.
return true if the year is divisible by 4 but not by 100
return false for the remaining values
Thank you.

Answer 1

I can't seems to return the method back to the main
Not sure where has gone wrong...
here is my code
import javax.swing.*;
public class ZellerTester
    public static void main(String[]args)
    int day  = 28;
    int month = 2;
    int year = 2007;
    int z;
    boolean isLeapYear;
    String[] displayName = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
    if(month==1 || month==2) {
        if (isLeapYear = false)
            day = day-1;
          else
            day = day-2;
    if(month<3)
        month = month + 12;
    z = (1 + day + (month * 2) + (3 * (month + 1) / 5) +
         year + year / 4 + year / 400 - year/ 100) % 7;
    System.out.println("The day is " +displayName[z]);
public boolean isLeapYear(int year)
       if (year%400 == 0)
           return true;
       else if((year%4 == 0) && (year%100 != 0))
            return true;
       else
             return false;
}