How can i calculate the days between two user inputs that are to be determined once entered?

Question

I am wanting to calculate the days between the start date of cycle and end date of cycle. the user will input the dates. i want to be able to use that input to calculate how long the cycle last as numberofdays.

the following is my current code and basic idea of how i want it to run. I have seen similar posts but nothing towards using an unknown user date. Any help would be appreciated thank you.

import java.util.Scanner;
import java.util.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
import javax.swing.JOptionPane;
import javax.swing.*;
import java.awt.*;
import java.time.*;
import java.util.Calendar;

public class project1
{
    public static void main (String [] args)
    {
        int StartDate = 0;                                                                      //Declaring Number of Toppings
        int EndDate = 0 ;                                                                   //Declaring Charge Per Topping in decimal


    Scanner inNumber= new Scanner (System.in);                                                          //Crate Scanner for input of number of toppings
    Scanner inText = new Scanner(System.in);                                                            //Creat Scanner for input of Name of Customers

    System.out.println("                 Female Calendar Entry System                    ");
    System.out.println( " "  ) ;


    String CustomersName = " ";
    System.out.print( "Please enter your name ==> ") ;
    CustomersName = inText.nextLine();                                                              //Inputing Customers Name

    System.out.println( " "  ) ;

    Date thisDate= new Date();
    SimpleDateFormat dateForm = new SimpleDateFormat ("dd/MM/Y");
    String startDate = dateForm.format(thisDate);
    System.out.println("                 Todays Date " +(dateForm.format(thisDate)));

    System.out.println( " "  ) ;

    // To take the input
    Scanner scanner = new Scanner(System.in);
    System.out.println("Enter Cycle start date ");

    String date = scanner.next();

    SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/Y");
    Date date2=null;
    System.out.println( " "  ) ;  
    Scanner scanner2 = new Scanner(System.in);
    System.out.println("Enter Cycle end date ");
    String date3 = scanner.next();
    SimpleDateFormat date3Format = new SimpleDateFormat("dd/MM/Y");
    Date date4=null;

        System.out.println("\n\n--- Female Calender Results ---");                              //Recipt for pizza order with name number of topings and overal price
        System.out.println( " "  ) ;
        System.out.println("Client Name: " + CustomersName);
        System.out.println("Lenght of cycle:")  ; // this should have the number of days the cycle lasted
        System.out.println("Aproximently next cycle: " + (" "));  // this should have 28 days end date of cycles
        System.out.println(" ");
    }
}