How to print multiple values for a true if statement in Java?

package leapYear;

import java.util.Scanner;
import javax.swing.JOptionPane;

public class leapYear {

    public static void main (String[] args){

    String yearInput = JOptionPane.showInputDialog("Enter the year here: ");
    Scanner inputScanner = new Scanner(yearInput);
    int year = inputScanner.nextInt();
    inputScanner.close();

    boolean leapYear = false;
    {

    if (year % 400 == 0)
    {
        leapYear = true;
    }

    else if (year % 100 == 0)
    {
        leapYear = false;
    }

    else if (year % 4 == 0)
    {
        leapYear = true;
    }

    else
    {
        leapYear = false;
    }

    if (leapYear)
        JOptionPane.showMessageDialog(null, year + " IS a leap year!");

    else JOptionPane.showMessageDialog(null, year + " is NOT a leap year!");
    }
}
}

Basically what I want to try to do, is to put in a year between say, 500-1000, and for the program to print every single leap year in that time period. I'm new to coding and have no idea how to go about this. Thanks.