How do I format user input into a date variable?

How do i take the user inputted day, month and year then store in a dd-mm-yyyy format? I can get everything to work except combining them into a date and storing them in the startDate variable. I also don't think startMonth will be accessible as it's in a switch case but I'm very new to java and unsure.

public static void carBookingDates() {

    int carNumber;
    int startYear;
    int startDay;
    int startMonth;
    int daysInMonth = 0;
    int endYear;
    int endMonth;
    int endDay;
   
    Scanner input = new Scanner(System.in);

    System.out.println("To make a booking:");
    System.out.printf("        Select a car number from the car list: ");
    carNumber = input.nextInt();
    System.out.println("");
    System.out.println("Enter a booking start date.");
    System.out.printf("Please enter the year - for example '2022': ");
    startYear = input.nextInt();
    while (startYear < 2022 || startYear > 2030) {
        System.out.println("Invalid year, please try again: ");
        System.out.printf("Please enter the year - for example '2022': ");
        startYear = input.nextInt();
    }
    System.out.printf("Please enter the month - for example '6': ");
    startMonth = input.nextInt();
    while (startMonth < 1 || startMonth > 12) {
        System.out.println("Invalid month, please try again: ");
        System.out.printf("Please enter the month - for example '6': ");
        startMonth = input.nextInt();
    }
    switch (startMonth) {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            daysInMonth = 31;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            daysInMonth = 30;
            break;
        case 2:
            if (((startYear % 4 == 0)
                    && !(startYear % 100 == 0))
                    || (startYear % 400 == 0)) {
                daysInMonth = 29;
            } else {
                daysInMonth = 28;
            }
            break;
        default:
            System.out.println("Invalid month.");
            break;
    }
    System.out.printf("Please enter the day number - for"
            + " example '18': ");
    startDay = input.nextInt();
    while (startDay > daysInMonth || startDay <= 0) {
        System.out.println("Invalid day, plese try again");
        System.out.printf("Please enter the day number - for"
                + " example '18': ");
        startDay = input.nextInt(); 
        LocalDate startDate() = LocalDate.parse(startDay + "-" + StartMonth "-" + startYear);
    }
}