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Is it possible to create a text file and then on the same run or runtime of the code also read and write in these files? Java

I was working on a Uni project for the end of the semester. The program is a simple bank system. My issue is that when the program first launches it creates a "Log" folder. Then when an account object is created using a Constructor a new txt file is created in the folder with the name of the account holder. Up until here I have managed to do it.
The issue is that when closing the program via the option menu but before closing the program, all the details from all the created objects (which are stored in a array) are written in their respective files following the order they are stored in the object array but on the first run the files are created but nothing is written in them.
Then on the 2nd run if I close the program again the details are written correctly. Can I have some suggestions please I could not find anything regarding this online?
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);
}
}
I have updated the post showing how I fixed it and providing all my classes. Please do not mind the messy code as I am first trying it out with a switch and then will ditch that when the time comes and use GUI as soon as I learn how to use it. Also I know that the classes can be organized better but BankAccount and eBanking are 2 salvaged classes I used on a different exercise.

I think I have found a solution. I just remembered that when using FileWriter if a file does not exist it creates one automatically. So i have cancelled the method which creates a file whenever a new object is created and now whenever the program is closed the files are created if needed or overwritten if they already exist.
I have provided all the current code on my program and the fix I implemented on FileManagment class

Allow user input for the number of threads for Fibonacci Sequence and Factorial Calculation using multithreading

I want to use scanner for user input for the number of threads to run. So far, this java code is able to run both the number of the Fibonacci sequences and factorial calculation based on user input. How do I do allow user input for the number of threads?:
import java.io.IOException;
import java.util.Scanner;
class Fibonacci extends Thread {
#Override
public void run() {
int n1=0, n2=0, n3=1;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the amount of Fibonacci: ");
int number = sc.nextInt();
for(int i=1; i<=number; i++) {
n1 = n2;
n2 = n3;
n3 = n1 + n2;
System.out.println(n1 + " ");
}
}
}
class Factorial extends Thread {
#Override
public void run() {
try {
long fact = 1;
int i = 1, n;
Scanner input = new Scanner(System.in);
System.out.print("Enter a number for the calculation of Factorial: ");
n = input.nextInt();
input.close();
while(i<=n)
{
fact = fact * i;
i++;
}
System.out.println("Factorial of "+n+" is: "+fact);
} catch (NumberFormatException ex) {
}
}
}
public class Assignment02 {
public static void main(String args[]) throws IOException {
Scanner input = new Scanner(System.in);
System.out.println("1.Fibonacci");
System.out.println("2.Factorial");
System.out.println("Choose your Option:");
String line = input.nextLine();
int option = Integer.parseInt(line);
switch (option) {
case 1:
System.out.println("Fibonacci Sequence SELECTED");
try {
Fibonacci fib = new Fibonacci();
fib.start();
fib.join();
} catch (Exception e) {
}
break;
case 2:
System.out.println("Factorial SELECTED");
try {
Factorial fact = new Factorial();
fact.start();
fact.join();
} catch (Exception e) {
}
break;
default:
System.out.println("Choose a valid option");
break;
}
}
}

Are my loops preventing me from getting the expected output?

My goal is to determine, for a pair of integers, whether the second integer is a multiple of the first. My code is as follows:
import java.util.Scanner;
public class Multiples {
public static void main(String [] args) {
boolean run = true;
while(run) {
Scanner input = new Scanner(System.in);
System.out.print("Enter one number:");
int num1 = input.nextInt();
System.out.print("Enter a second number:");
int num2 = input.nextInt();
boolean result = isMultiple(num1, num2);
if(result) {
System.out.println(num2 + " is a multiple of " + num1);
} else {
System.out.println(num2 + " is not a multiple of " + num1);
}
System.out.print("Do you want to enter another pair(y/n)?");
run = YesOrNo(input.next());
}
}
public static boolean YesOrNo(String a) {
if(a.equals("y"))
return true;
else
return false;
}
public static boolean isMultiple (int x , int y) {
if(y % x == 0)
return true;
else
return false;
}
}
This is my output:
This is the expected output:
The expected output is confusing me.

update a variable in a different class

How do I make amount() in class Casino.java store the total value and allow it to be returned to the class Roulette.java.
When I use:
int amount = Casino.amount();
It gives me several hundred lines of errors.
What I want done is to run the game number() and store the value into Casino.amount()
Please note in class Roulette.java there is a function called amountUpdate() which should update Casino.amount().
This is class Casino.java
package Casino;
import java.util.*;
public class Casino {
static String player = "";
static int playAmount = 0;
public static void main(String[] args) {
System.out.println("Welcome to Michael & Erics Casino!");
player();
ask();
start();
}
public static String player() {
if (player.equals("")) {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter your name : ");
player = sc.nextLine();
}
return player;
}
public static void ask() {
Scanner sc = new Scanner(System.in);
System.out.println("How much would you like to play with? ");
playAmount = sc.nextInt();
if (playAmount < 1) {
System.out.println("Please enter a value that is more than $1");
playAmount = 0;
}
System.out.println("You are playing with: $" + playAmount + "\n");
}
public static int amount() {
int amount = playAmount;
if (Roulette.amountUpdate() >= 1) {
amount += Roulette.amountUpdate();
}
return amount;
/*if (Blackjack.amountUpdate() >= 1)
amount += Blackjack.amountUpdate();
return amount;*/
}
public static void start() {
System.out.println("Which table would you like to play at?");
System.out.println("1: Blackjack");
System.out.println("2: Roulette");
System.out.println("3: Check Balance");
System.out.println("4: Exit");
Scanner sc = new Scanner(System.in);
int table = sc.nextInt();
switch (table) {
case 1:
//blackjack.main(new String[]{});
break;
case 2:
Roulette.main(new String[]{});
break;
case 3:
System.out.println("You have : $" + playAmount);
start();
break;
case 4:
System.exit(0);
break;
}
}
}
This is class Roulette.java
package Casino;
import java.util.*;
import java.lang.*;
public class Roulette {
public static void main(String[] args) {
System.out.println("Welcome to the roulette table " + Casino.player());
placeBet();
amountUpdate();
//number();
}
public static int amountUpdate() {
int amount = 0;
if (number() > 0) {
amount += number();
}
if (br() > 0) {
amount += br();
}
if (oe() > 0) {
amount += oe();
}
if (third() > 0) {
amount += third();
}
return amount;
}
public static void placeBet() {
Scanner sc_Choice = new Scanner(System.in);
System.out.println("What would you like to bet on?");
System.out.println("1: Numbers");
System.out.println("2: Black or Red");
System.out.println("3: Odd or Even");
System.out.println("4: One Third");
System.out.println("5: Count Chips");
System.out.println("6: Restart");
int choice = sc_Choice.nextInt();
if (choice > 0 && choice < 7) {
switch (choice) {
case 1:
number();
break;
case 2:
br();
break;
case 3:
oe();
break;
case 4:
third();
break;
case 5:
System.out.println(Casino.amount());
break;
case 6:
Casino.main(new String[]{});
break;
}
} else {
System.out.println("You must choose between 1 and 6");
}
}
public static int number() {
Boolean betting = true;
//int amount = Casino.amount();
int amount = 5000;
int number;
int winnings;
String reply;
int betX;
int betAgain = 1;
Scanner sc_Number = new Scanner(System.in);
ArrayList<Integer> list = new ArrayList<Integer>();
ArrayList<Integer> bet = new ArrayList<Integer>();
while (betAgain == 1) {
System.out.println("What number would you like to place a bet on?");
int listCheck = sc_Number.nextInt();
if (listCheck >= 0 && listCheck <= 36) {
list.add(listCheck);
} else {
System.out.println("You must choose a number between 0 and 36");
}
System.out.println("How much do you want to bet?");
betX = sc_Number.nextInt();
if (betX > amount) {
System.out.println("You have insufficient funds to make that bet");
number();
} else if (betX < 1) {
System.out.println("You must bet more than 1$");
} else {
bet.add(betX);
amount = amount - betX;
}
System.out.println("Do you want to bet on more numbers?");
reply = sc_Number.next();
if (reply.matches("no|No|false|nope")) {
betAgain = betAgain - 1;
//No - Don't bet again
} else {
betAgain = 1;
//Yes - Bet again
}
int result = wheel();
System.out.println("Spinning! .... The number is: " + result);
for (int i = 0; i < bet.size(); i++) {
if (list.get(i) == result) {
winnings = bet.get(i) * 35;
System.out.println("Congratulations!! You won: $" + winnings);
amount = amount + winnings;
System.out.println("Current Balance: " + amount);
betAgain = betAgain - 1;
} else {
System.out.println("Sorry, better luck next time!");
System.out.println("Current Balance: " + amount);
betAgain = betAgain - 1;
}
}
betAgain = betAgain - 1;
}
return amount;
}
public static int wheel() {
Random rnd = new Random();
int number = rnd.nextInt(37);
return number;
}
//NOT WORKING - AFTER MAKING A BET IT RUNS Number()
public static int br() {
Scanner sc_br = new Scanner(System.in);
int amount = Casino.amount();
int winnings;
System.out.println("Would you like to bet on Black or Red?");
String replyBR = sc_br.nextLine();
boolean black;
//****************
if (replyBR.matches("black|Black")) {
black = true;
} else {
black = false;
}
System.out.println("How much would you like to bet?");
int betBR = sc_br.nextInt();
if (betBR > amount) {
System.out.println("You have insufficient funds to make that bet");
br();
} else if (betBR < 1) {
System.out.println("You must bet more than 1$");
br();
} else {
amount = amount - betBR;
}
//*****************
boolean resultColour = colour();
if (resultColour == black) {
winnings = betBR * 2;
//PRINT OUT WHAT COLOUR!!!
System.out.println("Congratulations!! You won: $" + winnings);
amount = amount + winnings;
System.out.println("Current Balance: " + amount);
} else {
System.out.println("Sorry, better luck next time!");
}
System.out.println("Current Balance: " + amount);
return amount;
}
public static boolean colour() {
Random rnd = new Random();
boolean colour = rnd.nextBoolean();
return colour;
}
//NOT WORKING - AFTER MAKING A BET IT RUNS Number()
public static int oe() {
Scanner sc_oe = new Scanner(System.in);
int amount = Casino.amount();
int winnings;
System.out.println("Would you like to bet on Odd or Even?");
String replyOE = sc_oe.next();
System.out.println("How much would you like to bet?");
int betOE = sc_oe.nextInt();
if (betOE > amount) {
System.out.println("You have insufficient funds to make that bet");
oe();
}
amount = amount - betOE;
boolean resultOE = oddOrEven();
//PRINT OUT IF IT WAS ODD OR EVEN
if (resultOE == true) {
winnings = betOE * 2;
System.out.println("Congratulations!! You won: $" + winnings);
amount = amount + winnings;
System.out.println("Current Balance: " + amount);
} else {
System.out.println("Sorry, better luck next time!");
System.out.println("Current Balance: " + amount);
}
return amount;
}
public static boolean oddOrEven() {
Random rnd = new Random();
boolean num = rnd.nextBoolean();
return num;
}
//NOT WORKING - AFTER MAKING A BET IT RUNS Number()
public static int third() {
Scanner sc_Third = new Scanner(System.in);
int amount = Casino.amount();
int winnings;
System.out.println("Would you like to bet on 1st, 2nd or 3rd third?");
String replyT = sc_Third.next();
System.out.println("How much would you like to bet?");
int betT = sc_Third.nextInt();
if (betT > amount) {
System.out.println("You have insufficient funds to make that bet");
third();
}
amount = amount - betT;
boolean resultT = thirdResult();
//PRINT OUT WHAT NUMBER IT WAS AND IF IT WAS IN WHICH THIRD
if (resultT == true) {
winnings = betT * 3;
System.out.println("Congratulations!! You won: $" + winnings);
amount = amount + winnings;
System.out.println("Current Balance: " + amount);
} else {
System.out.println("Sorry, better luck next time!");
System.out.println("Current Balance: " + amount);
}
return amount;
}
public static boolean thirdResult() {
Random rnd = new Random();
int num = rnd.nextInt(2);
if (num == 0) {
return true;
} else {
return false;
}
}
}

Looks like you're probably running into a StackOverflowException. When you call Casino.amount() inside of Roulette.number(), it then calls Roulette.amountUpdate(), which then calls Roulette.number(). Your methods are stuck in an infinite loop like this. You'll need to redesign your code such that these 3 functions are not all dependent on each other.
Your code is terse, so it's hard to help you fully solve the problem, but I believe you would benefit from splitting up your "amount" variable into separate entities. Keep things like bet amount, winnings, and such separate until you need to combine them.
Another issue you may run into is thatRoulette.amountUpdate() is called twice in Casino.amount(), but Roulette.amountUpdate() will not necessarily return the same thing both times. Consider storing the return value from the first call instead of calling it twice.

same functionality but without using continue and break?

how would you restructure this code so it doesnt use continue and break? i have tried but have had no luck. thanks
import java.util.*;
public class q6 {
public static void main(String args[]) {
int Number;
Scanner sc = new Scanner(System.in);
while (true) // seemingly an infinite loop
{
System.out.print("Enter a positive integer ");
System.out.println("or 0 to exit ");
Number = sc.nextInt();
if (Number == 0)
break;
else if (Number < 0);
System.out.print("Squareroot of " + Number);
System.out.println(" = " + Math.sqrt(Number));
//continue lands here at end of current iteration
}
//break lands here
System.out.println("a zero was entered");
}
}

import java.util.*;
public class q6 {
public static void main(String args[]) {
int Number;
Scanner sc = new Scanner(System.in);
System.out.print("Enter a positive integer ");
System.out.println("or 0 to exit ");
Number = sc.nextInt();
while (Number>0)// looping while number >0
{
System.out.print("Squareroot of " + Number);
System.out.println(" = " + Math.sqrt(Number));
Number = sc.nextInt();
}
System.out.println("a zero was entered");
}

import java.util.*;
class q6 {
public static void main(String args[]) {
int Number;
Scanner sc = new Scanner(System.in);
while (instruct() && (Number=sc.nextInt())!=0) // seemingly an infinite loop
{
if (Number < 0);
System.out.print("Squareroot of " + Number);
System.out.println(" = " + Math.sqrt(Number));
//continue lands here at end of current iteration
}
//break lands here
System.out.println("a zero was entered");
}
static boolean instruct()
{
System.out.print("Enter a positive integer ");
System.out.println("or 0 to exit ");
return true;
}
}