【解決方法】次の質問のコーディングを手伝ってください

Java で銀行アプリを作成する必要がありましたが、エラーが発生し続けていますが、どこから来たのかわかりません

私が試したこと：

import javax.swing.*;
public class BankApp
{
   
    public static void main (String[] args) 
    {
        double bal; // Balance of savings account
        int sel = 0; // Menu selection

        bal = Double.parseDouble(JOptionPane.showInputDialog(null, "Enter your Account Number :", "Welcome To Nakeisha's Bank",JOptionPane.QUESTION_MESSAGE));

        while (sel != 4)
        {
            sel = Integer.parseInt(JOptionPane.showInputDialog(null, """
                                                                     Select an option: 
                                                                     1. Withdraw 
                                                                     2. Deposit 
                                                                     3. Check balance 
                                                                     4. Exit"""));

            switch(sel)
            {
                case 1 -> withdraw(bal);

                case 2 -> deposit(bal);

                case 3 -> CheckBalance(bal);

                default -> {
                        JOptionPane.showMessageDialog(null, "Thank you for using Nakeisha's Bank.");
                        System.exit(0);
                }
            }
        }
    }

    public static double withdraw (double bal)
    {
        double withdrawAmt; // Amount to withdraw

        withdrawAmt = Double.parseDouble(JOptionPane.showInputDialog(null, "Enter the amount you want to withdraw (in R):", "Withdrawals", JOptionPane.QUESTION_MESSAGE));

        while (bal < withdrawAmt)
        {
            JOptionPane.showMessageDialog(null, "The amount you have entered is more than your savings balance.\nPlease re-enter.", "Withdrawals", JOptionPane.ERROR_MESSAGE);
            withdrawAmt = Double.parseDouble(JOptionPane.showInputDialog(null, "Enter amount to withdraw (in R):", "Withdrawals", JOptionPane.QUESTION_MESSAGE));
        }
        bal -= withdrawAmt;
        return bal;
    }

    public static double deposit (double bal)
    {
        double depositAmt; // Amount to deposit

        depositAmt = Double.parseDouble(JOptionPane.showInputDialog(null, "Enter the amount you want to deposit (in R):", "Deposits", JOptionPane.QUESTION_MESSAGE));

        while (depositAmt <= 0)
        {
            JOptionPane.showMessageDialog(null, "The amount you have entered is a negative amount or zero.\nPlease re-enter.", "Deposits", JOptionPane.ERROR_MESSAGE);
            depositAmt = Double.parseDouble(JOptionPane.showInputDialog(null, "Enter the amount you want to deposit (in R):", "Deposits", JOptionPane.QUESTION_MESSAGE));
        }
        bal += depositAmt;
        return bal;
    }

    public static void CheckBalance (double bal)
    {
        JOptionPane.showMessageDialog(null, "Your balance is: R" +bal, "Check Balance", JOptionPane.INFORMATION_MESSAGE);
    }

}