If statement troubles 7 hours in

I am 4 weeks into Java class with 0 experience. I'm asked to create a program which asks use to input the numerical representation of a month example 1 would be january & also an input for the year and have the program output display the month how many days in the month and if it is a leap year. This is one of my many attempts shortened. What am I doing wrong it starts with january n matter the input.

package leapmonth;

import javax.swing.JOptionPane;

public class LeapMonth {
    public static void main(String[] args) {

        int Year;
        int MonthNumber;

    String MonthString;    


    JOptionPane.showMessageDialog(null, " HELLO, WELCOME TO LEAPMONTH ");
    MonthString = JOptionPane.showInputDialog( " Please enter the numerical respresentation of the month");
    MonthNumber = Integer.parseInt(MonthString);
    MonthString = JOptionPane.showInputDialog( " Please enter the year");
    Year = Integer.parseInt(MonthString);

    if( MonthNumber == 1 && Year % 4 == 0 && Year % 100 != 0 || Year % 400 == 0)
    {
     JOptionPane.showMessageDialog(null,"The month is January. " + "January has 31 days in it" + " and is also a leap year "); 
    }   
    else if( MonthNumber == 1 && Year % 4 != 0 && Year % 100 == 0 || Year % 400 != 0)
    {
     JOptionPane.showMessageDialog(null,"The month is January. " + "January has 31 days in it" + " and it is not a leap year ");   
    }
    else if( MonthNumber == 2 && Year % 4 == 0 && Year % 100 != 0 || Year % 400 ==0)
    {
     JOptionPane.showMessageDialog(null,"The month is February. " + "February has 29 days in it because this is a leap year ");  
    } 
    else if( MonthNumber == 2 && Year % 4 != 0 && Year % 100 == 0 || Year % 400 != 0)
    {
    JOptionPane.showMessageDialog(null,"The month is February. " + "February has 28 days in it because this is not a leap year ");
    }
   }
}