Im not sure whats the problem with my code, as it displays invalid when i enter a valid date input

Question

Im using Java and mySql I have already done my code to prompt user to enter a date in the format DDMMYY and then store the info into the database, however, when i enter a valid date such as 121221, it will say "invalid date, please re-enter" Im not sure whats the problem..

this is my validation class

public class Validation {
    
    public static boolean isValidDate(String date) {
        
        String day = date.substring(0,2);
        String month = date.substring(2,4);
        String year = date.substring(4,6);

        int i = Integer.parseInt(day);
        int j = Integer.parseInt(year);
        int k = Integer.parseInt(month);

        if (k%2 !=0 || k == 8 || k == 10 || k == 12) {
            if(i<=0 || i>31) {
                return false;
            }
        }else if (k == 2) {
            if(i<=0 || i>28) {
                return false;
            }
        }else if (k%2 == 0 || k == 9 || k == 11) {
            if (i<=0 || i>30) {
                return false;
            }
        }

        if(j<22 || j>100) {
            return false;
        }
        return true;
    }

    public boolean isValidTransactionId(int transactionId) {
        
        return true;
    }
}

my UI class

package view;

import java.util.*;
import java.text.*;
import controller.DBController;
import controller.Validation;
import model.Transaction;
import model.Member;

public class UserInterface {
    DBController db;
    Validation vd;
    Scanner scan;
    Random rand;
    String date;
    boolean invalid;
    int menuChoice, memberChoice;
    Transaction transaction;

    public UserInterface()throws Exception{
        db= new DBController();
        scan = new Scanner(System.in);
        rand = new Random();
        transaction =  new Transaction();

    }

    public void MainMenu()throws Exception {
        System.out.println("Welcome to SuperFun Theme Park!");

        do {
            System.out.print("Main Menu\n");
            System.out.println("1. New Ticket Transaction");
            System.out.println("2. Modify a Ticket Transaction");
            System.out.println("3. Delete a Ticket Transaction");
            System.out.println("4. View Ticket Transactions");
            System.out.println("5. Exit");

            System.out.print("Enter a number (1-5): ");
            menuChoice = scan.nextInt();
            scan.nextLine();

            switch(menuChoice) {
            case 1: newTicket(); break;
            case 2: modifyTicket(); break;
            case 3: deleteTicket(); break;
            case 4: viewAllTransactions(); break;
            case 5: System.out.println("Thank you. Have a nice day!"); break;
            default: System.out.println("Invalid input. Please re-enter.\n");break;
            }

        }while(menuChoice!=5);
    }

    public void dateInput()throws Exception{
        do {
            if(menuChoice ==1 ) {
                System.out.print("Enter ticket date (DDMMYY): ");
                date = scan.nextLine();
                transaction.setDate(date);

            }else if (menuChoice == 4) {
                System.out.print("Enter start date (DDMMYY): ");
                date = scan.nextLine();
                transaction.setDate(date);
            }
            invalid = false;

            if(!vd.isValidDate(date)) {
                invalid = true;
            }else
                invalid = false;

        }while(invalid);
    }

    public void displayMemberInfo()throws Exception{
        String result[] = null;
        System.out.printf("\n%s %17s %20s\n","Index","Name", "Phone Number");

        result = db.retrieveMemberInfo();
        for(String temp: result)
            System.out.println(temp);
    }

    public void newTicket() throws Exception{
        int member=0, numOfMemberTickets=0, transactionId =0;
        int memberTicket=80, nonMemberTicket=100, total=0, num=0;
        boolean full = false, repeat= false;

        //auto generate transaction id //100-200
        int upperbound = 200;
        int lowerbound = 100;

        do {
            transactionId = rand.nextInt(upperbound - lowerbound)+ lowerbound;
            transaction.setId(transactionId);
        }while(db.idExists(transaction.getId()));

        //display transaction id
        System.out.println("\nTransaction Id: " + transaction.getId());

        //prompt user to enter ticket date
        //validation for date
        do {
            dateInput();
            db.maximumTicket(transaction.getDate());
            if(db.sum>=100) {
                System.out.println("Tickets are fully booked for the day. Please re-enter date.\n");
                full = true;
            }else {
                System.out.printf("Number of tickets left for %s are %d\n" , date, 100-db.sum);
                full = false;
            }
        }while(full);

        //ask for total number of tickets then ask for members tickets
        do {
            System.out.print("Enter number of ticket(s) wanted: ");
            num = scan.nextInt();
            scan.nextLine();
            transaction.setTicketNum(num);

            if(transaction.getTicketNum() > 100-db.sum)
                System.out.println("Number of ticket(s) wanted exceeded availability. Please re-enter. ");
        }while(transaction.getTicketNum() > 100-db.sum);

        //if member, must choose which member
        //loop through member info for validation 
        do {
            repeat=false;
            do {
                System.out.print("Are there ticket(s) for member(s)? (1-yes 2-no): ");
                member = scan.nextInt();
                scan.nextLine();

                if(member !=1 && member !=2)
                    System.out.println("Invalid input. Please re-enter.");

            }while(member !=1 && member !=2);

            if(member==1) {
                do {
                    System.out.print("Enter the number of member tickets: ");
                    numOfMemberTickets = scan.nextInt();
                    scan.nextLine();

                    if(numOfMemberTickets<=0)
                        System.out.println("Invalid number of tickets. Please re-enter.");
                }while(numOfMemberTickets<=0);

                //display member info table
                displayMemberInfo();

                for(int cnt=0; cnt<numOfMemberTickets; cnt++) {
                    do {
                        System.out.print("\nPlease enter index number of member: ");
                        memberChoice = scan.nextInt();

//                      if(db.memberExists(transaction.getId())) {
//                          System.out.println("Member are only allowed to purchase one ticket in a day. Please re-enter.");
//                          repeat = true;
//                      }else
                        db.insertNumber(memberChoice, transaction.getId());

                    }while(memberChoice<=0);
                }
            }
        }while(repeat);

        //calculate and display total price 
        total = (numOfMemberTickets * memberTicket) + (Math.abs((transaction.getTicketNum() - numOfMemberTickets)) * nonMemberTicket);
        transaction.setTotal(total);
        System.out.println("Total price: RM" + transaction.getTotal());

        //save data into database
        boolean success = db.insertInfo(transaction.getDate(), transaction.getId(), transaction.getTicketNum(), transaction.getTotal());
        if(success)
            System.out.println("Transaction record inserted successfully.\n");
        else
            System.out.println("Error in inserting record.\n");
    }

    public void modifyTicket() throws Exception{
        int transactionId=0, newTicketNum=0, newNumOfMemberTicket=0, newTotal=0, change=0;
        String newDate="";
        //enter transaction id
        do {
            System.out.print("Enter transaction id: ");
            transactionId = scan.nextInt();
            scan.nextLine();
            transaction.setId(transactionId);
            if(!db.idExists(transaction.getId()))
                System.out.println("Transaction id does not exists. Please re-enter.");
        }while(!db.idExists(transaction.getId()));
        

        //display details
        System.out.printf("\n%-4s %20s %25s %20s\n","Ticket Date", "Transaction Id", "Number of Tickets", "Total Price");
        db.displayRecord(transaction.getId());

        //user can edit date, number and members' phone number
        System.out.print("\nEnter new ticket date: ");
        newDate = scan.nextLine();
        transaction.setDate(newDate);

        System.out.print("Enter new number of tickets(including members' tickets): ");
        newTicketNum = scan.nextInt();
        scan.nextLine();
        transaction.setTicketNum(newTicketNum);

        System.out.print("Enter new number of member ticket(s): ");
        newNumOfMemberTicket = scan.nextInt();
        scan.nextLine();

        System.out.print("Is there a change in member(s)? (1-yes 2-no): ");
        change = scan.nextInt();
        scan.nextLine();

        if(change==1) {
            displayMemberInfo();
            for(int cnt=0; cnt<newNumOfMemberTicket; cnt++) {
                do {
                    System.out.print("\nPlease enter index number of member: ");
                    memberChoice = scan.nextInt();

                    db.updateNumber(memberChoice, transactionId);

                }while(memberChoice<=0);
            }
        }

        //recalculate total price
        newTotal = (newNumOfMemberTicket * 80) + (Math.abs(newTicketNum - newNumOfMemberTicket)* 100);
        transaction.setTotal(newTotal);

        //update database
        boolean success = db.updateInfo(transaction.getDate(), transaction.getTicketNum(), transaction.getTotal(), transaction.getId());
        if(success)
            System.out.println("Information updated successfully.\n");
        else
            System.out.println("Error in updating information.\n");

    }

    public void deleteTicket()throws Exception{
        int transactionId=0, choice =0;
        //enter transaction id
        do {
            System.out.print("Enter transaction id: ");
            transactionId = scan.nextInt();
            scan.nextLine();

            if(!db.idExists(transactionId))
                System.out.println("Transaction id does not exists. Please re-enter.");
        }while(!db.idExists(transactionId));

        transaction.setId(transactionId);

        //display all information of that transaction
        System.out.printf("\n%-4s %20s %25s %20s\n","Ticket Date", "Transaction Id", "Number of Tickets", "Total Price");
        db.displayRecord(transactionId);

        //re-confirm whether to delete
        do {
            System.out.print("\nConfirm delete? (1-yes 2-no): ");
            choice = scan.nextInt();
        }while(choice !=1 && choice !=2);

        //delete from database
        if(choice == 1) {
            boolean success = db.deleteInfo(transaction.getId());

            if (success)
                System.out.println("Transaction Info deleted successfully.\n");
            else
                System.out.println("Error in deleting transaction info.\n");
        }else
            System.out.println("Returning to main menu...\n");
    }

    public void viewAllTransactions() throws Exception{
        String result[] = null;
        String date2 ="", letter="";

        //enter start date
        dateInput();

        switch(date.substring(2,4)) {
        case "01": letter = "Jan"; break;
        case "02": letter = "Feb"; break;
        case "03": letter = "Mar"; break;
        case "04": letter = "Apr"; break;
        case "05": letter = "May"; break;
        case "06": letter = "June"; break;
        case "07": letter = "July"; break;
        case "08": letter = "Aug"; break;
        case "09": letter = "Sep"; break;
        case "10": letter = "Oct"; break;
        case "11": letter = "Nov"; break;
        case "12": letter = "Dec"; break;
        }

        date2 = date.substring(0,2) + letter + "20" + date.substring(4,6);

        //show all records from start date
        //display error if no matching one
        boolean success = db.matchingDate(transaction.getDate());
        if(success) {
            System.out.println("\nTransaction Report from " + date2);
            System.out.printf("%-4s %20s %25s %20s\n","Ticket Date", "Transaction Id", "Number of Tickets", "Total Price");
            result = db.retrieveAllInfo(date);
            for(String temp: result)
                System.out.println(temp);
        }else
            System.out.println("Error in finding date entered.");

        System.out.println("\nReturning to main menu...\n");
    }

}

transaction class

public void setDate(String date) {
        if(Validation.isValidDate(date))
            this.date =  date;
        else
            System.out.println("Date is invalid. Please re-enter.");
    }

Answer 1

Honestly, those if checks are kind of hard to look at. Try this:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;

public class dateTime {

    public static void main(String[] args) throws ParseException {
        SimpleDateFormat datefr = new SimpleDateFormat("dd-MM-yy");
        datefr.setTimeZone(TimeZone.getTimeZone("UTC"));
        datefr.setLenient(false);
        try {
            Date date = datefr.parse("12-10-21");
            System.out.println(true);
        } catch (ParseException e) {
            System.out.println(false);
            System.out.println(e.getMessage());
        }
    }

}