是否可以創建一個文本文件，然后在代碼的同一運行或運行時也讀寫這些文件？ Java

Question

學期末我正在做一個 Uni 項目。 該程序是一個簡單的銀行系統。 我的問題是，當程序首次啟動時，它會創建一個“日志”文件夾。 然后，當使用構造函數創建帳戶 object 時，會在文件夾中創建一個新的 txt 文件，其中包含帳戶持有人的姓名。 到這里為止，我已經設法做到了。

問題是，當通過選項菜單關閉程序但在關閉程序之前，所有創建的對象（存儲在數組中）的所有詳細信息都按照它們存儲在 object 數組中的順序寫入各自的文件中但是在第一次運行時，文件被創建但沒有寫入任何內容。

然后在第二次運行時，如果我再次關閉程序，詳細信息將被正確寫入。 請給我一些建議，我在網上找不到任何相關信息？

import java.util.Scanner;
import java.io.*;

public class FileManagement {

  static String pathnameFile = "src\\Log";
  static File directory = new File(pathnameFile);
  static String[] allFiles = directory.list();

  public static void createFolder() {
    File logFile = new File(pathnameFile);
    if (!logFile.exists()) {
      logFile.mkdir();
    }
  }
  public static void writeFiles() throws IOException {
    FileWriter writer;
    for (int i = 0; i < allFiles.length; i++) {
      writer = new FileWriter(pathnameFile + "\\" + allFiles[i]);
      writer.write("accountName= " + eBanking.accounts[i].getAccountName() + "\n");
      writer.write("PIN= " + eBanking.accounts[i].getPIN() + "\n");
      writer.write("balance= " + Integer.toString(eBanking.accounts[i].getBalance()) + "\n");
      writer.write("Object ID stored in RAM= " + eBanking.accounts[i].toString() + "\n");
      writer.close();
    }
  }
//original method
  /*public static void readFiles() {
    Scanner reader;
    for (int i = 0; i < allFiles.length; i++) {
      reader = new Scanner(pathnameFile + allFiles[i]);
    }
  }*/
//My solution
  public static void readFiles() throws IOException{
        if(directory.exists() == false || allFiles == null) {
            return;
        }
        Scanner reader;
        File currentFile;
        String[] data = new String[4];
        for(int i = 0; i < allFiles.length; i++) {
            currentFile = new File(pathnameFile + "\\" +allFiles[i]);
            reader = new Scanner(currentFile);
            int count = 0;
            while(reader.hasNextLine()) {
                if(!reader.hasNext()) {
                    break;
                }
                reader.next();
                data[count] = reader.next();
                count++;
            }
            reader.close();
            String accountName = data[0];
            String PIN = data[1];
            int balance = Integer.parseInt(data[2]);
            eBanking.accounts[i] = new eBanking(accountName, PIN, balance);
        }
    }
}

import java.util.Scanner;
import java.io.*;

public class App {
    public static eBanking currentAccount;
    public static void mainMenu() throws Exception{
        while (true) {
            Scanner input = new Scanner(System.in);
            System.out.println("""
                --------------------------------------------------------
                1. Log in
                2. Register
                0. Exit.
                --------------------------------------------------------
                    """);
            int menuOption = input.nextInt();
            switch (menuOption) {
                case 1 -> {
                    System.out.println("Please enter your account name and PIN below.");
                    System.out.print("Account name: ");
                    String accountName = input.next();
                    System.out.print("PIN: ");
                    String PIN = input.next();
                    System.out.println();

                    for (int i = 0; i < eBanking.accounts.length; i++) {
                        if (accountName.equals(eBanking.accounts[i].getAccountName()) && PIN.equals(eBanking.accounts[i].getPIN())) {
                            eBanking.accounts[i].welcome();
                            currentAccount = eBanking.accounts[i];
                            break;
                        }
                    }
                    menu();
                }
                case 2 -> {
                    System.out.println("Please enter the account name, PIN and inital balance of your new account.");
                    System.out.print("Account name:");
                    String accountNameRegister = input.next();
                    System.out.print("PIN: ");
                    String registerPIN = input.next();
                    System.out.print("Initial balance: ");
                    int initialBalance = input.nextInt();

                    currentAccount = new eBanking(accountNameRegister, registerPIN, initialBalance);
                    menu();
                }
                default -> {
                    FileManagement.writeFiles();
                    System.exit(0);
                }
            }
        }
    }
    public static void menu() {
        Scanner input = new Scanner(System.in); 
        while (true) {
            System.out.println("""
                --------------------------------------------------------
                1. Show your balance.
                2. Withdraw money.
                3. Deposit money.
                4. Change your PIN.
                5. Transfer money to another person.
                0. Back.
                --------------------------------------------------------
                    """);
            int menuOption = input.nextInt();
            switch (menuOption) {
                case 1 -> {
                    currentAccount.showBalance();
                }
                case 2 -> {
                    System.out.println("Please enter the amount you want to withdraw: ");
                    int withdrawAmount = input.nextInt();
                    currentAccount.withdraw(withdrawAmount);
                }
                case 3 -> {
                    System.out.println("Please enter the amount you want to deposit: ");
                    int depositAmount = input.nextInt();
                    currentAccount.deposit(depositAmount);
                }
                case 4 -> {
                    currentAccount.changePIN();
                }
                case 5 -> {
                    System.out.println("Please enter the amount you want to send: ");
                    int amount = input.nextInt();
                    System.out.println("Please enter the account number you want to send the money to: ");
                    String transferAccount = input.next();// Me nextLine(); duhet ta shkruaj 2 here qe ta marri, duke perdor next(); problemi evitohet (E kam hasur edhe tek c++ kete problem)  
                    System.out.println("The amount of money is completed");
                    currentAccount.transfer(amount, transferAccount);
                }
                case 0 -> {
                    return;
                }
                default -> {
                    System.out.println("Please enter a number from the menu list!");
                }
            }
        }
    }
    public static void main(String[] args) throws Exception {
        FileManagement.createFolder();
        FileManagement.readFiles();
        mainMenu();
    }
}

import java.util.Scanner;
import java.io.*;

public class eBanking extends BankAccount {
    // Variable declaration
    Scanner input = new Scanner(System.in);
    private String accountName;
    private String accountID;

    public static eBanking[] accounts = new eBanking[100];

    // Methods
    public String getAccountName() {
        return accountName;
    }
    public void welcome() {
        System.out.println("---------------------------------------------------------------------------------------");
        System.out.println("Hello " + accountName + ". Welcome to eBanking! Your account number is: " + this.accountID);
    }
    public void transfer(int x, String str) {
        boolean foundID = false;
        withdraw(x);
        if (initialBalance == 0) {
            System.out.println("Transaction failed!");
        } else if (initialBalance < x) {
            for(int i = 0; i < numberOfAccount; i++) {
                if (str.equals(accounts[i].accountID)) {
                    accounts[i].balance += initialBalance;
                    System.out.println("Transaction completed!");
                    foundID = true;
                } 
            }
            if (foundID = false) {
                System.out.println("Account not found. Transaction failed. Deposit reimbursed");
                this.balance += initialBalance;
                return;
            }
        } else {
            for(int i = 0; i <= numberOfAccount; i++) {
                if (str.equals(accounts[i].accountID)) {
                    accounts[i].balance += x;
                    System.out.println("Transaction completed!");
                    foundID=true;
                    return;
                }
            }
            if (foundID = false) {
                System.out.println("Account not found. Transaction failed. Deposit reimbursed");
                this.balance += x;
                return;
            }
        }
    }
    // Constructors
    public eBanking(String name){
        int firstDigit = (int)(Math.random() * 10);
        int secondDigit = (int)(Math.random() * 10);
        int thirdDigit = (int)(Math.random() * 10);
        int forthDigit = (int)(Math.random() * 10);
        accountID = this.toString();

        PIN = Integer.toString(firstDigit) + secondDigit + thirdDigit + forthDigit; //Nuk e kuptova perse nese i jap Integer.toString te pares i merr te gjitha 
        balance = 0;                                                                //dhe nuk duhet ta perseris per the gjitha
        accountName = name;
        accounts[numberOfAccount] = this;
        numberOfAccount++;

        System.out.println("---------------------------------------------------------------------------------------");
        System.out.println(accountName + ": Your balance is " + balance + ", your PIN is: " + PIN + " and your account number is: " + accountID);
    }
    public eBanking(String name, String pin, int x){
        if (checkPIN(pin) == false) {
            System.out.println("Incorrect PIN format!");
            return;
        }
        accountID = this.toString();
        accountName = name;
        balance = x;
        PIN = pin;
        accounts[numberOfAccount] = this;
        numberOfAccount++;

        welcome();
    }
}

import java.util.Scanner;

public abstract class BankAccount {
    // Variable declaration
    protected String PIN;
    protected int balance;

    public static int numberOfAccount = 0;
    protected static int initialBalance; // E kam perdorur per te bere menune me dinamike sidomos per metoden transfer();

    //Methods
    //Balance
    public int getBalance() {
        return balance;
    }
    public void showBalance() {
        System.out.println("The total balance of the account is " + balance);
    }
    public void withdraw(int x) {
        initialBalance = balance;
        if (balance == 0) {
            System.out.println("The deduction has failed due to lack of balance!");
            return;
        }
        if (balance < x) {
            balance = 0;
            System.out.println("The deduction of " + initialBalance + " from your balance is completed!");
        } else {
            balance -= x;
            System.out.println("The deduction of " + x + " from your balance is completed!");
        }
    }
    public void deposit(int x) {
        balance += x;
        System.out.println("You have made a deposit of  " + x + " and your current balance is " + balance);
    }
    
    //PIN
    public String getPIN() {
        return PIN;
    }
    public void changePIN() {
        Scanner input = new Scanner(System.in);
        
        System.out.print("Please enter your previous PIN: ");
        String tryPIN = input.nextLine();

        if (tryPIN.equals(PIN)) {
            System.out.print("Please enter your new PIN: ");
            String newPIN = input.nextLine();
            if (checkPIN(newPIN) == false) {
                System.out.println("The PIN is not in the correct format!");
            } else {
                System.out.println("The PIN has been changed");
                PIN = newPIN;
            }
        } else {
            System.out.println("The PIN does not match!");
        }
    }
    protected static boolean checkPIN(String str) {
        boolean isValid;

        if(str.length() != 4) {
            isValid = false;
        } else {
            try {
                int x = Integer.parseInt(str);
                isValid = true;
            } catch (NumberFormatException e) {
                isValid = false;
            }
        }
        return isValid;
    }
    //Kjo metode duhet per testim
    public void getDetails() {
        System.out.println(balance + " and PIN " + PIN);
    }
}

我已經更新了帖子，展示了我是如何修復它並提供我所有的課程的。 請不要介意這些亂七八糟的代碼，因為我首先用一個開關嘗試它，然后在時機成熟時放棄它，並在我學會如何使用它后立即使用 GUI。 我也知道可以更好地組織課程，但 BankAccount 和 eBanking 是我在不同練習中使用的 2 個挽救課程。

Answer 1

我想我找到了解決辦法。 我只記得在使用 FileWriter 時，如果文件不存在，它會自動創建一個。 因此，我取消了每當創建新的 object 時創建文件的方法，現在每當程序關閉時，如果需要，就會創建文件，如果文件已經存在，則會被覆蓋。

我已經在我的程序中提供了所有當前代碼以及我在 FileManagment class 上實施的修復