Develop Reference

How would I make the readability better in Java

I feel like the amount of while loops nested into each other isn't too readable and could be simplified down but I'm not sure how I can simplify it down. Could someone let me know what I would have to do to simplify this. I'm not sure how I would convert these while loops to methods because my variables are in the main method. I'm pretty new to Java so any help would be appreciated.
import java.util.Scanner;
public class Payroll
{
public static void main(String[] args)
{
//init scanner
Scanner reader = new Scanner(System.in);
//var
boolean repeat = true; //keeps or breaks loop
String strHWage; //input for hourly wage
double dblHWage; //clctd for hourly wage from strHWage
String strHours; //input for hours worked
double dblHours; //clctd for hours worked
String strOverHours; //input for overtime hours
double dblOverHours; //clctd for overtime hours
double totalPay; //clctd total pay
//dscrp of prgrm to usr
System.out.println();
System.out.println("Calculate your weekly pay");
System.out.println("Entering \"exit\" at any type will bring you back to the manager");
System.out.println();
//setting repeat to true
repeat = true;
while (repeat == true)
{
//rqst input for hourly wage
System.out.print("Enter hourly wage: $");
strHWage = reader.next();
System.out.println();
outerloop:
while (isNumeric(strHWage))
{
if (strHWage.equalsIgnoreCase("exit"))
{
repeat = false;
//bring to manager
System.out.println("Program terminated, going to manager\n");
Manager.main(args);
}
else if (isNumeric(strHWage))
{
//str -> dbl
dblHWage = Double.parseDouble(strHWage);
//rqst hours worked
System.out.print("Enter hours worked: ");
strHours = reader.next();
System.out.println();
while (isNumeric(strHours))
{
if(strHours.equalsIgnoreCase("exit"))
{
repeat = false;
//bring to manager
System.out.println("Program terminated, going to manager\n");
Manager.main(args);
}
else if (isNumeric(strHours))
{
//str -> dbl
dblHours = Double.parseDouble(strHours);
//rqst overtime hours worked
System.out.print("Enter overtime hours worked: ");
strOverHours = reader.next();
System.out.println();
while (isNumeric(strOverHours))
{
if (strOverHours.equalsIgnoreCase("exit"))
{
repeat = false;
//bring to manager
System.out.println("Program terminated, going to manager\n");
Manager.main(args);
}
else if (isNumeric(strOverHours))
{
//str -> dbl
dblOverHours = Double.parseDouble(strOverHours);
//clctd $ earned
totalPay = (dblHWage * dblHours) + ((dblHWage * 1.5) * dblOverHours);
//prnt total $ earned
System.out.println("your weekly pay is $" + String.format("%.2f", totalPay));
System.out.println();
break outerloop;
}
}
if (!isNumeric(strOverHours))
{
System.out.println("please enter an actual number.\n");
}
}
}
if (!isNumeric(strHours))
{
System.out.println("please enter an actual number.\n");
}
}
}
if (!isNumeric(strHWage))
{
System.out.println("please enter an actual number.\n");
}
}
}
//FUNCITON TO CHECK STR NUMERIC BEFORE PARSING
public static boolean isNumeric(String str)
{
try
{
Double.parseDouble(str); //parses string if string value is numerical
return true;
}
catch(NumberFormatException ex) //returns false and does not parse if string value is not numerical
{
return false;
}
}
}

You can simplify your code by breaking it down into smaller functions. I have done some refactoring in your code, but this can further be improved:-
import java.util.Scanner;
public class Payroll {
//setting repeat to true
static Boolean repeat = true;
public static void main(String[] args) {
//init scanner
Scanner reader = new Scanner(System.in);
//dscrp of prgrm to usr
System.out.println("\nCalculate your weekly pay");
System.out.println("Entering \"exit\" at any type will bring you back to the manager\n");
while (repeat) {
//rqst input for hourly wage
System.out.print("Enter hourly wage: $");
String strHWage = reader.next();
System.out.println();
outerloop:
if (isNumeric(strHWage)) {
//str -> dbl
double dblHWage = Double.parseDouble(strHWage);
//rqst hours worked
System.out.print("Enter hours worked: ");
String strHours = reader.next();
System.out.println();
if (isNumeric(strHours)) {
//str -> dbl
double dblHours = Double.parseDouble(strHours);
//rqst overtime hours worked
System.out.print("Enter overtime hours worked: ");
String strOverHours = reader.next();
System.out.println();
if (isNumeric(strOverHours)) {
//str -> dbl
double dblOverHours = Double.parseDouble(strOverHours);
//clctd $ earned
double totalPay = (dblHWage * dblHours) + ((dblHWage * 1.5) * dblOverHours);
//prnt total $ earned
System.out.println("your weekly pay is $" + String.format("%.2f", totalPay));
System.out.println();
break outerloop;
} else {
validateInput(strOverHours, args);
}
} else {
validateInput(strHours, args);
}
} else {
validateInput(strHWage, args);
}
}
}
public static void validateInput(String input, String[] args) {
if (input.equalsIgnoreCase("exit")) {
repeat = false;
//bring to manager
System.out.println("Program terminated, going to manager\n");
Manager.main(args);
} else {
System.out.println("please enter an actual number.\n");
}
}
//FUNCITON TO CHECK STR NUMERIC BEFORE PARSING
public static boolean isNumeric(String str) {
try {
Double.parseDouble(str); //parses string if string value is numerical
return true;
} catch (NumberFormatException ex) //returns false and does not parse if string value is not numerical
{
return false;
}
}
}

Handle Scanner exception on Java program

I am working on a school project. I have all the functionality working but when I submit the project through Mimir, during deposits and withdraws it gives the following error:
Enter the amount you want to Deposit :$Exception in thread "main" java.util.NoSuchElementException
13 at java.util.Scanner.throwFor(Scanner.java:862)
14 at java.util.Scanner.next(Scanner.java:1485)
15 at java.util.Scanner.nextDouble(Scanner.java:2345)
16 at BankAccount.deposit(BankAccount.java:24)
17 at SavingsAccountDemo.main(SavingsAccountDemo.java:30)
The project does says the following: Please make sure that your classes throw appropriate exceptions when an attempt is made to insert invalid data.
I tried to add the try and catch with java.util.InputMismatchException e but it doesn't seem to be fixing it. I think it's because the userInput is a double and they are entering something different. Any ideas how can I fix that? Here is the code:
///SavingsAccountDemo class
import java.util.*;
public class SavingsAccountDemo {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
double startingBalance;
double interestRate;
String userInput;
System.out.print("Enter beginning balance :$");
startingBalance = keyboard.nextDouble();
System.out.print("Enter interest rate(whole number) :%");
interestRate = keyboard.nextDouble();
double bal = startingBalance;
double rate = interestRate;
BankAccount ba = new BankAccount(startingBalance, interestRate);
BankDemo sv = new BankDemo(bal, rate);
while(startingBalance > -1) {
try {
System.out.println("Enter D for deposit" + "\nEnter W to Withdraw" + "\nEnter B for Balance" +
"\nEnter M for Monthly Process" + "\nEnter E to Exit");
userInput = keyboard.next().toLowerCase();
if("d".equals(userInput)) {
ba.deposit();
} else if("w".equals(userInput)) {
ba.withdraw();
} else if("b".equals(userInput)) {
ba.totalBalance();
} else if("m".equals(userInput)) {
ba.monthlyProcess();
} else if("e".equals(userInput)) {
ba.exit();
break;
}
else {
System.out.print("Error, option not valid\n");
}
}
catch (java.util.InputMismatchException e) {
System.out.print("Error");
}
}
}
}
///BankAccount class
import java.util.*;
public class BankAccount {
protected double balance;
protected double numDeposits;
protected double numWithdrawals;
protected double annualRate;
protected double monthlyServCharg;
protected boolean active;
Scanner keyboard = new Scanner(System.in);
public BankAccount(double startingBalance, double interestRate) {
balance = startingBalance;
annualRate = interestRate /= 100.0;
if(balance < 25) {
active = false;
} else
active = true;
}
public void deposit() {
try {
double valueD;
System.out.print("Enter the amount you want to Deposit :$");
valueD = keyboard.nextDouble();
if(valueD < 0) {
System.out.println("Error: Must enter positive value\n");
}
if( balance + valueD >= 25 && !active) {
System.out.print("Your account is now ACTIVE\n");
active = true;
}
balance += valueD;
numDeposits++;
}
catch (java.util.InputMismatchException e){
keyboard.nextLine();
}
}
public void withdraw() {
try {
double valueW;
System.out.print("Enter the amount you want to withdraw :$");
valueW = keyboard.nextDouble();
if(valueW < 0) {
System.out.println("Error: Must enter positive value\n");
}
balance -= valueW;
numWithdrawals++;
if(balance < 0) {
System.out.print("ERROR: Transaction declined!! This transaction will cause overdraft or zero balance\n");
balance += valueW;
} else if(balance <= 25 && active) {
System.out.print("Your balance is less than minimum balance. Your account is now INACTIVE\n");
active = false;
}
if(numWithdrawals > 4) {
balance --;
System.out.print("You have exceeded monthly limit of withdrawals. Fee of $1 charged\n");
}
}
catch (java.util.InputMismatchException e) {
keyboard.nextLine();
}
}
public void totalBalance() {
System.out.printf("Your Balance is: %.2f\n", balance);
}
public void calcInterest() {
double monRate = annualRate / 12;
double monInt = balance * monRate;
balance += monInt;
}
public void monthlyProcess() {
calcInterest();
balance -= monthlyServCharg;
numWithdrawals = 0;
numDeposits = 0;
monthlyServCharg = 0;
System.out.printf("Your Balance after Monthly process is: %.2f\n", balance);
}
public void exit() {
totalBalance();
System.out.print("Thank you. Bye");
}
}

How to return Scanner.in value from the method to another method

I want to make some simple program which will count monthly rate of product. There is two inputs: cost of the product - between 100-10000 and number of rates - between 6-48. I wanted to do it like in the code below:
import java.util.Scanner;
public class Calculator {
Scanner sc = new Scanner (System.in);
double productCost;
int numberOfRates;
double loanInterestRate;
double monthlyRate;
Double print () {
Calculator c = new Calculator();
System.out.println ("Enter the value of your product from 100 to 10 000 : ");
productCost=sc.nextDouble();
if (productCost < 100){
System.out.println ("You have to choose price between 100 to 10000. Try again: ");
c.print();
} else if (productCost >10000){
System.out.println ("You have to choose price between 100 to 10000. Try again: ");
c.print();
} else if (productCost >= 100 || productCost <=10000){
c.print1();
return = productCost;
// how to return productCost to be used in next method print1()?
}
else return null;
}
void print1(){
Calculator c = new Calculator();
System.out.println ("Now enter how many rates do you want to pay from 6 to 48: ");
numberOfRates=sc.nextInt();
if (numberOfRates<6){
System.out.println ("You can't choose this number of rates. Choose between 6-48: ");
c.print1();
} else if (numberOfRates>48){
System.out.println ("You can't choose this number of rates. Choose between 6-48: ");
c.print1();
} else if (numberOfRates>=6 || numberOfRates<=12) {
loanInterestRate=1.025;
monthlyRate = (productCost*loanInterestRate)/numberOfRates;
System.out.printf("Your monthly rate is: "+ "%.2f%n",monthlyRate);
} else if (numberOfRates>=13 || numberOfRates <=24 ) {
loanInterestRate=1.05;
monthlyRate = (productCost*loanInterestRate)/numberOfRates;
System.out.printf("Your monthly rate is: "+ "%.2f%n",monthlyRate);
} else if (numberOfRates >=25|| numberOfRates<=48){
loanInterestRate=1.1;
monthlyRate = (productCost*loanInterestRate)/numberOfRates;
System.out.printf("Your monthly rate is: "+ "%.2f%n",monthlyRate);
}
}
}
And the main method only calling the method from the other class.
public class MonthlyRate {
public static void main(String[] args) {
Calculator calc = new Calculator();
calc.print();
// TODO code application logic here
}
}
And what is the problem, I don't know how to return the "double productCost" from the method "print()". productCost is taking from the input and this is double but NetBeans showing me that it's not correct type. Can anybody help me understand where is the problem?

Simply do
return productCost;
return is a keyword, not a variable. It 'returns' the given value and exits the function, so that the entity calling the function can do this:
public static void main(String[] args) {
...
double cost = calc.print(); // note calc.print() PRODUCES a value, which we assign to `cost`
...
}
You can then do whatever you want with cost (or whatever you choose to name the variable), including passing it to another function.

Your program needs changes in a few places. I have done those changes and written below the updated program:
import java.util.Scanner;
class Calculator {
Scanner sc = new Scanner(System.in);
double productCost;
int numberOfRates;
double loanInterestRate;
double monthlyRate;
void print() {
Calculator c = new Calculator();
System.out.println("Enter the value of your product from 100 to 10 000 : ");
productCost = sc.nextDouble();
if (productCost < 100) {
System.out.println("You have to choose price between 100 to 10000. Try again: ");
c.print();
} else if (productCost > 10000) {
System.out.println("You have to choose price between 100 to 10000. Try again: ");
c.print();
} else if (productCost >= 100 || productCost <= 10000) {
print1(productCost);
}
}
void print1(double productCost) {
Calculator c = new Calculator();
System.out.println("Now enter how many rates do you want to pay from 6 to 48: ");
numberOfRates = sc.nextInt();
if (numberOfRates < 6) {
System.out.println("You can't choose this number of rates. Choose between 6-48: ");
c.print1(productCost);
} else if (numberOfRates > 48) {
System.out.println("You can't choose this number of rates. Choose between 6-48: ");
c.print1(productCost);
} else if (numberOfRates >= 6 || numberOfRates <= 12) {
loanInterestRate = 1.025;
monthlyRate = (productCost * loanInterestRate) / numberOfRates;
System.out.printf("Your monthly rate is: " + "%.2f%n", monthlyRate);
} else if (numberOfRates >= 13 || numberOfRates <= 24) {
loanInterestRate = 1.05;
monthlyRate = (productCost * loanInterestRate) / numberOfRates;
System.out.printf("Your monthly rate is: " + "%.2f%n", monthlyRate);
} else if (numberOfRates >= 25 || numberOfRates <= 48) {
loanInterestRate = 1.1;
monthlyRate = (productCost * loanInterestRate) / numberOfRates;
System.out.printf("Your monthly rate is: " + "%.2f%n", monthlyRate);
}
}
}
public class MonthlyRate {
public static void main(String[] args) {
Calculator calc = new Calculator();
calc.print();
// TODO code application logic here
}
}
It is easy to understand the changes after comparing your program with this updated program. Nevertheless, feel free to let me know if you need any further help on this.

Bank Account Java Program

I am creating a bank account program for my java class that is suppose to manage up to 5 different bank accounts. The program has to allow the creation of a new account, which I have done, allow deposit and withdraw, which is also done, the 2 parts I cannot get to work are 1: the bank can only have up to 5 accounts, so if a 6th is trying to be created, a message comes up saying that 5 are already created, and 2: one of the options has to print out all the account balances of current accounts in the bank.
This is my code as of now:
import java.util.Scanner;
public class Bankapp {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
Bank myBank = new Bank();
int user_choice = 2;
do {
//display menu to user
//ask user for his choice and validate it (make sure it is between 1 and 6)
System.out.println();
System.out.println("1) Open a new bank account");
System.out.println("2) Deposit to a bank account");
System.out.println("3) Withdraw to bank account");
System.out.println("4) Print account balance");
System.out.println("5) Quit");
System.out.println();
System.out.print("Enter choice [1-5]: ");
user_choice = s.nextInt();
switch (user_choice) {
case 1:
System.out.println("Enter a customer name");
String cn = s.next();
System.out.println("Enter a opening balance");
double d = s.nextDouble();
System.out.println("Account was created and it has the following number: " + myBank.openNewAccount(cn, d));
break;
case 2: System.out.println("Enter a account number");
int an = s.nextInt();
System.out.println("Enter a deposit amount");
double da = s.nextDouble();
myBank.depositTo(an, da);
break;
case 3: System.out.println("Enter a account number");
int acn = s.nextInt();
System.out.println("Enter a withdraw amount");
double wa = s.nextDouble();
myBank.withdrawFrom(acn, wa);
break;
case 4: System.out.println("Enter a account number");
int anum = s.nextInt();
myBank.printAccountInfo(anum);
break;
case 5:
System.out.println("Here are the balances " + "for each account:");
case 6:
System.exit(0);
}
}
while (user_choice != '6');
}
static class Bank {
private BankAccount[] accounts; // all the bank accounts at this bank
private int numOfAccounts = 5; // the number of bank accounts at this bank
// Constructor: A new Bank object initially doesn’t contain any accounts.
public Bank() {
accounts = new BankAccount[5];
numOfAccounts = 0;
}
// Creates a new bank account using the customer name and the opening balance given as parameters
// and returns the account number of this new account. It also adds this account into the account list
// of the Bank calling object.
public int openNewAccount(String customerName, double openingBalance) {
BankAccount b = new BankAccount(customerName, openingBalance);
accounts[numOfAccounts] = b;
numOfAccounts++;
return b.getAccountNum();
}
// Withdraws the given amount from the account whose account number is given. If the account is
// not available at the bank, it should print a message.
public void withdrawFrom(int accountNum, double amount) {
for (int i =0; i<numOfAccounts; i++) {
if (accountNum == accounts[i].getAccountNum() ) {
accounts[i].withdraw(amount);
System.out.println("Amount withdrawn successfully");
return;
}
}
System.out.println("Account number not found.");
}
// Deposits the given amount to the account whose account number is given. If the account is not
// available at the bank, it should print a message.
public void depositTo(int accountNum, double amount) {
for (int i =0; i<numOfAccounts; i++) {
if (accountNum == accounts[i].getAccountNum() ) {
accounts[i].deposit(amount);
System.out.println("Amount deposited successfully");
return;
}
}
System.out.println("Account number not found.");
}
// Prints the account number, the customer name and the balance of the bank account whose
// account number is given. If the account is not available at the bank, it should print a message.
public void printAccountInfo(int accountNum) {
for (int i =0; i<numOfAccounts; i++) {
if (accountNum == accounts[i].getAccountNum() ) {
System.out.println(accounts[i].getAccountInfo());
return;
}
}
System.out.println("Account number not found.");
}
public void printAccountInfo(int accountNum, int n) {
for (int i =0; i<numOfAccounts; i++) {
if (accountNum == accounts[i].getAccountNum() ) {
System.out.println(accounts[i].getAccountInfo());
return;
}
}
System.out.println("Account number not found.");
}
}
static class BankAccount{
private int accountNum;
private String customerName;
private double balance;
private static int noOfAccounts=0;
public String getAccountInfo(){
return "Account number: " + accountNum + "\nCustomer Name: " + customerName + "\nBalance:" + balance +"\n";
}
public BankAccount(String abc, double xyz){
customerName = abc;
balance = xyz;
noOfAccounts ++;
accountNum = noOfAccounts;
}
public int getAccountNum(){
return accountNum;
}
public void deposit(double amount){
if (amount<=0) {
System.out.println("Amount to be deposited should be positive");
} else {
balance = balance + amount;
}
}
public void withdraw(double amount)
{
if (amount<=0){
System.out.println("Amount to be withdrawn should be positive");
}
else
{
if (balance < amount) {
System.out.println("Insufficient balance");
} else {
balance = balance - amount;
}
}
}
}//end of class
The program runs fine, I just need to add these two options, and cannot get them to work properly, how would I go about doing this? Also, options 3 and 4 should not work if no accounts have been created yet. Thanks in advance.
UPDATE: this is what I tried, I keep getting a this method must return type int error.
public int openNewAccount(String customerName, double openingBalance) {
if(numOfAccounts > 5)
{
System.out.println("5 accounts already exist");
}
else
{
BankAccount b = new BankAccount(customerName, openingBalance);
accounts[numOfAccounts] = b;
numOfAccounts++;
return b.getAccountNum();
}
}
UPDATE 2: I added a return statement, now when it runs it will open accounts up to number 5, but for every account after number 5 it just says the account number is 5 again instead of not opening an account.
public int openNewAccount(String customerName, double openingBalance) {
if(numOfAccounts > 5)
{
System.out.println("5 accounts already exist");
}
else
{
BankAccount b = new BankAccount(customerName, openingBalance);
accounts[numOfAccounts] = b;
numOfAccounts++;
return b.getAccountNum();
}
return numOfAccounts;
}

Its pretty simple. Create a list of size 5 and add the account into that list when user is created one. Before adding just make a check whether list size <= 5. If it is true, go ahead and add the account, otherwise throw an error
For option 2, just iterate through the list and display the results

1; in the openNewBank account method; before creating the new Bank account and increasing the count by 1; check if the number of account is already at 5 or higher and if it is dont create the account and dont increase the count.
2: Loop through the number of account variable and print.

I added password system to it. and nice looking account num.
Code :
import java.io.*;
import java.util.Random;
public class Computer_Bank_of_India {
public static int NewRandom(int min, int max) {
Random rand = new Random();
int randomNum = rand.nextInt((max - min) + 1) + min;
return randomNum;
}
public static void main(String args[])throws IOException, InterruptedException {
InputStreamReader ir = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(ir);
Bank myBank = new Bank();
int Option = 1, Account_Number, Account_Password, atempts = 0, Pass;
String Name;
double Balance, Money;
System.out.println("Please wait, the system is starting...");
while(Option !=5) {
Thread.sleep(4000);
System.out.println("1) Open a new bank account");
Thread.sleep(250);
System.out.println("2) Deposit to a bank account");
Thread.sleep(250);
System.out.println("3) Withdraw to bank account");
Thread.sleep(250);
System.out.println("4) Print the detailed account information including last transactions");
Thread.sleep(250);
System.out.println("5) Quit");
System.out.println();
System.out.print(" Enter Option [1-5]: ");
Option = Integer.parseInt(br.readLine());
switch(Option) {
case 1 : System.out.println("Enter a customer name :");
Name = br.readLine();
System.out.println("Enter a opening balance :");
Balance = Double.parseDouble(br.readLine());
Thread.sleep(250);
System.out.println("Creating your account....");
Thread.sleep(500);
int[] arrDetails= myBank.AddNewAccount(Name, Balance);
System.out.println("Account Has been created\n Account number: " + arrDetails[0]+"\nYour password : "+ arrDetails[1]);
break;
case 2 : System.out.println("Enter a account number :");
Account_Number = Integer.parseInt(br.readLine());
System.out.println("Enter a account password :");
Account_Password = Integer.parseInt(br.readLine());
System.out.println("Enter a deposit amount :");
Money = Double.parseDouble(br.readLine());
myBank.Deposit(Account_Number, Account_Password, Money);
break;
case 3 : System.out.println("Enter a account number :");
Account_Number = Integer.parseInt(br.readLine());
System.out.println("Enter a account password :");
Account_Password = Integer.parseInt(br.readLine());
System.out.println("Enter a deposit amount :");
Money = Double.parseDouble(br.readLine());
myBank.Withdraw(Account_Number, Account_Password, Money);
break;
case 4 : System.out.println("Enter a account number :");
Account_Number = Integer.parseInt(br.readLine());
System.out.println("Enter a account password :");
Account_Password = Integer.parseInt(br.readLine());
myBank.Transactions(Account_Number, Account_Password);
break;
case 5 : System.out.println("Please Enter your password :");
Pass = Integer.parseInt(br.readLine());
if(Pass == myBank.Password) {
System.out.println(" System shutting down.....");
Option = 5;
break;
}
else {
Thread.sleep(250);
System.out.println("You have enter a wrong password. Please try again");
Option = 0;
}
default: System.out.println("Invalid option. Please try again.");
}
}
}
static class Bank {
private int Password=2684;
private BankAccount[] accounts;
private int numOfAccounts;
public Bank() {
accounts = new BankAccount[100];
numOfAccounts = 0;
}
public int [] AddNewAccount(String Name, Double Balance) {
BankAccount b = new BankAccount(Name, Balance);
accounts[numOfAccounts] = b;
numOfAccounts++;
int Acc = b.getAccountNum()[0];
int Pass = b.getAccountNum()[1];
int[]details = {Acc, Pass};
return details;
}
public void Withdraw(int Account_Number, int pass, double Money) {
for (int i =0; i<numOfAccounts; i++) {
int a = accounts[i].getAccountNum()[0];
if (Account_Number == a) {
int p = accounts[i].getAccountNum()[1];
if( pass == p) {
accounts[i].withdraw(Money);
return;
}
}
}
System.out.println(" You have entered a wrong Account number or Password.");
}
public void Deposit(int Account_Number, int pass, double Money) {
for (int i =0; i<numOfAccounts; i++) {
int a = accounts[i].getAccountNum()[0];
if (Account_Number == a) {
int p = accounts[i].getAccountNum()[1];
if( pass == p) {
accounts[i].deposit(Money);
return;
}
}
}
System.out.println(" You have entered a wrong Account number or Password.");
}
public void Transactions(int Account_Number, int pass) {
for(int i = 0;i<numOfAccounts; i++) {
int a = accounts[i].getAccountNum()[0];
if (Account_Number == a ) {
int p = accounts[i].getAccountNum()[1];
if( pass == p) {
System.out.println(accounts[i].getAccountInfo());
System.out.println(" Last transaction: " + accounts[i].getTransactionInfo(accounts[i].getNumberOfTransactions()-1));
return;
}
}
}
System.out.println(" You have entered a wrong Account number or Password.");
}
}
static class BankAccount{
private int User_Password;
private int accountNum;
private String customerName;
private double balance;
private double[] transactions;
private String[] transactionsSummary;
private int numOfTransactions;
private static int noOfAccounts=0;
public String getAccountInfo(){
return " Account number: " + accountNum + "\n Customer Name: " + customerName + "\n Balance:" + balance +"\n";
}
public String getTransactionInfo(int n) {
String transaction = transactionsSummary[n];
return transaction;
}
public BankAccount(String abc, double xyz){
customerName = abc;
balance = xyz;
noOfAccounts ++;
User_Password = NewRandom(1000, 9999);
accountNum = NewRandom(800000000, 999999999);
transactions = new double[100];
transactionsSummary = new String[100];
transactions[0] = balance;
transactionsSummary[0] = "A balance of : Rs" + Double.toString(balance) + " was deposited.";
numOfTransactions = 1;
}
public int [] getAccountNum(){
int account = accountNum;
int Pass = User_Password;
int [] details = {account, Pass};
return details;
}
public int getNumberOfTransactions() {
return numOfTransactions;
}
public void deposit(double amount){
if (amount<=0) {
System.out.println("Amount to be deposited should be positive");
} else {
balance = balance + amount;
transactions[numOfTransactions] = amount;
transactionsSummary[numOfTransactions] = "Rs." + Double.toString(amount) + " was deposited.";
numOfTransactions++;
System.out.println(" Amount deposited successfully");
}
}
public void withdraw(double amount) {
if (amount<=0){
System.out.println("Amount to be withdrawn should be positive");
}
else {
if (balance < amount) {
System.out.println("Insufficient balance");
} else {
balance = balance - amount;
transactions[numOfTransactions] = amount;
transactionsSummary[numOfTransactions] = "Rs." + Double.toString(amount) + " was withdrawn.";
numOfTransactions++;
System.out.println(" Amount Withdrawn successfully");
}
}
}
}
}

Arrays and bank accounts in Java

I am trying to write a simple Bank Account Management program that does the following:
Creates a new account with Account number and Balance taken from user and stored in an array
Selects an account (from the array)
Deletes the account selected
Withdraw and Deposit into account selected.
Problem: I don't understand what the my mistakes are.
I tried using different types of arrays for account number and balance storing, but I didn't not find the answer yet. I search the web and Stackoverflow for references, documentations, simple examples, but could not find any (the ones that I found, use some commands and things that I haven't learned yet so I can understand how they work). I am a beginner, I am still learning and would appreciate some advice. Thanks!
//Bank account class
public class account {
private int ANumber;
private double balance;
public account(double initialBalance, int accno) {
balance = initialBalance;
ANumber = accno;
}
public void deposit (double u_amm){
balance += u_amm;
}
public double withdraw(double amount) {
balance -= amount;
return amount;
}
public double getBalance() {
return balance;
}
public int getAccount(){
return ANumber;
}
}
And this is the Main class
import java.util.Scanner;
// main class
public class bankmain {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
// Menu starts from here
Scanner input = new Scanner(System.in);
System.out.println("Enter the option for the operation you need:");
System.out.println("****************************************************");
System.out.println("[ Options: ne - New Account de - Delete Account ]");
System.out.println("[ dp - Deposit wi - Withdraw ]");
System.out.println("[ se - Select Account ex - Quit ]");
System.out.println("****************************************************");
System.out.print("> "); //indicator for user input
String choice = input.next();
//Options
while(true){
if(choice == "ne"){
int nacc;
int bal;
int [][]array = new int[nacc][bal]; // Array for account and balance
System.out.print("Insert account number: ");
nacc =input.nextInt(); //-- Input nr for array insertion
System.out.print("Enter initial balance: ");
bal=input.nextInt(); //-- Input nr for array insertion
System.out.println("Current account: " + nacc + " " + "Balance " + bal);
break;
}
// account selection
if(choice.equals("se")){
System.out.println("Enter number of account to be selected: ");
//user input for account nr from array
System.out.println("Account closed.");
}
//close account
if(choice.equals("de")){
//array selected for closing
System.out.println("Account closed.");
}
// deposit
if(choice.equals("dp")){
System.out.print("Enter amount to deposit: ");
double amount = scan.nextDouble();
if(amount <= 0){
System.out.println("You must deposit an amount greater than 0.");
} else {
System.out.println("You have deposited " + (amount + account.getBalance()));
}
}
// withdrawal
if(choice.equals("wi")){
System.out.print("Enter amount to be withdrawn: ");
double amount = scan.nextDouble();
if (amount > account.balance()){
System.out.println("You can't withdraw that amount!");
} else if (amount <= account.balance()) {
account.withdraw(amount);
System.out.println("NewBalance = " + account.getBalance());
}
}
//quit
if(choice == "ex"){
System.exit(0);
}
} // end of menu loop
}// end of main
} // end of class

Your code was wrong on many levels - first try to work on your formatting and naming conventions so you don't learn bad habbits. Dont use small leters for naming classes, try to use full words to describe variables and fields, like in that Account.class example:
public class Account {
private Integer accountNumber;
private Double balance;
public Account(final Integer accountNumber, final Double initialBalance) {
this.accountNumber = accountNumber;
balance = initialBalance;
}
public Double deposit (double depositAmmount) {
balance += depositAmmount;
return balance;
}
public Double withdraw(double withdrawAmmount) {
balance -= withdrawAmmount;
return balance;
}
public Double getBalance() {
return balance;
}
public Integer getAccountNumber() {
return accountNumber;
}
}
Also try to use the same formatting(ie. spaces after brackets) in all code, so that it's simpler for you to read.
Now - what was wrong in your app:
Define the proper holder for your accounts i.e. HashMap that will hold the information about all accounts and will be able to find them by accountNumber.
HashMap<Integer, Account> accountMap = new HashMap<Integer, Account>();
This one should be inside your while loop, as you want your user to do multiple tasks. You could ommit the println's but then the user would have to go back to the top of the screen to see the options.
System.out.println("Enter the option for the operation you need:");
System.out.println("****************************************************");
System.out.println("[ Options: ne - New Account de - Delete Account ]");
System.out.println("[ dp - Deposit wi - Withdraw ]");
System.out.println("[ se - Select Account ex - Quit ]");
System.out.println("****************************************************");
System.out.print("> "); //indicator for user input
String choice = input.nextLine();
System.out.println("Your choice: " + choice);
You shouldn't compare Strings using '==' operator as it may not return expected value. Take a look at: How do I compare strings in Java? or What is the difference between == vs equals() in Java?. For safty use Objects equals instead, ie:
choice.equals("ne")
There was no place where you created the account:
Account newAccount = new Account(newAccountNumber, initialBalance);
You didn't use if-else, just if's. It should look more like that (why to check if the choice is 'wi' if it was already found to be 'ne'):
if(choice.equals("ne")) {
//doStuff
} else if choice.equals("se") {
//doStuff
} //and so on.
If your using Java version >= 7 then instead of if-else you can use switch to compare Strings.
There was no notification of the wrong option:
} else {
System.out.println("Wrong option chosen.");
}
You didn't close your Scanner object. This really doesn't matter here, as it's in main method and will close with it, but it's a matter of good habbits to always close your streams, data sources etc when done using it:
input.close();
So the whole code can look like this:
import java.util.HashMap;
import java.util.Scanner;
// main class
public class BankAccount {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
HashMap<Integer, Account> accountMap = new HashMap<Integer, Account>();
//Options
while(true) {
System.out.println("Enter the option for the operation you need:");
System.out.println("****************************************************");
System.out.println("[ Options: ne - New Account de - Delete Account ]");
System.out.println("[ dp - Deposit wi - Withdraw ]");
System.out.println("[ se - Select Account ex - Quit ]");
System.out.println("****************************************************");
System.out.print("> "); //indicator for user input
String choice = input.next();
System.out.println("Your choice: " + choice);
if(choice.equals("ne")) {
Integer newAccountNumber;
Double initialBalance;
Account newAccount;
// Array for account and balance
System.out.print("Insert account number: ");
newAccountNumber = input.nextInt(); //-- Input nr for array insertion
System.out.print("Enter initial balance: ");
initialBalance=input.nextDouble(); //-- Input nr for array insertion
newAccount = new Account(newAccountNumber, initialBalance);
accountMap.put(newAccountNumber, newAccount);
System.out.println("New Account " + newAccountNumber + " created with balance: " + initialBalance);
}
//select account
else if(choice.equals("se")) {
System.out.println("Enter number of account to be selected: ");
Integer accountToGetNumber = input.nextInt();
Account returnedAccount = accountMap.get(accountToGetNumber);
if (returnedAccount != null)
{
System.out.println("Account open. Current balance: " + returnedAccount.getBalance());
}
else
{
//user input for account nr from array
System.out.println("Account does not exist.");
}
}
//close account
else if(choice.equals("de"))
{
System.out.println("Enter number of account to be selected: ");
Integer accountToDeleteNumber = input.nextInt();
Account removedAccount = accountMap.remove(accountToDeleteNumber);
if (removedAccount != null)
{
System.out.println("Account " + removedAccount.getAccountNumber() + " has been closed with balance: " + removedAccount.getBalance());
}
else
{
//user input for account nr from array
System.out.println("Account does not exist.");
}
}
// deposit
else if(choice.equals("dp")) {
System.out.println("Enter number of account to deposit: ");
Integer accountToDeposit = input.nextInt();
System.out.print("Enter amount to deposit: ");
double amount = input.nextDouble();
if(amount <= 0){
System.out.println("You must deposit an amount greater than 0.");
} else {
accountMap.get(accountToDeposit).deposit(amount);
System.out.println("You have deposited " + (amount));
System.out.println("Current balance " + accountMap.get(accountToDeposit).getBalance());
}
}
// withdrawal
else if(choice.equals("wi")) {
System.out.println("Enter number of account to withdraw: ");
Integer accountToWithdraw = input.nextInt();
System.out.print("Enter amount to withdraw: ");
double amount = input.nextDouble();
if(amount <= 0) {
System.out.println("You must deposit an amount greater than 0.");
} else {
accountMap.get(accountToWithdraw).withdraw(amount);
System.out.println("You have deposited " + (amount));
System.out.println("Current balance " + accountMap.get(accountToWithdraw).getBalance());
}
}
//quit
else if(choice.equals("ex")) {
break;
} else {
System.out.println("Wrong option.");
} //end of if
} //end of loop
input.close();
} //end of main
} //end of class
There still is much to improve, i.e. input validation - but this should work for the begining.

You have written the above code, but it has many mistakes. You need to learn the The basics of Java programming.
I have modified your program to perform below operations :-
Create new account.
Select existing account.
Deposit amount.
Withdraw amount.
View balance.
Delete account.
Exit.
Account.java :
/**
* This class performs bank operations
*/
public class Account {
private int accNumber;
private double balance;
public Account(double initialBalance, int accNo) {
balance = initialBalance;
accNumber = accNo;
}
public void deposit(double amount) {
balance += amount;
}
public double withdraw(double amount) {
balance -= amount;
return amount;
}
public double getBalance() {
return balance;
}
public int getAccNumber() {
return accNumber;
}
}
BankMain.java :
public class BankMain {
private static double amount;
private static ArrayList<Account> accountList = new ArrayList<>();
private static Account selectedAccount;
private static boolean flag = false;
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
// Menu starts from here
Scanner input = new Scanner(System.in);
System.out.println("Enter the option for the operation you need:");
System.out
.println("****************************************************");
System.out
.println("[ Options: new - New Account del - Delete Account ]");
System.out
.println("[ dp - Deposit wi - Withdraw bal - Check balance ]");
System.out
.println("[ se - Select Account exit - Quit ]");
System.out
.println("****************************************************");
Account account = null;
while (true) {
System.out.println("> "); // indicator for user input
String choice = input.next();
// Options
switch (choice) {
case "new":
// Create new account
int accNo = 0;
int bal = 0;
System.out.println("Enter account number : ");
accNo = input.nextInt();
System.out.println("Enter initial balance: ");
bal = input.nextInt();
System.out.println("Current account: " + accNo + " "
+ "Balance " + bal);
account = new Account(bal, accNo);
accountList.add(account);
break;
case "se":
// select account
System.out
.println("Enter account number for further operations : ");
int selectedAcc = scan.nextInt();
System.out.println("Selected account : " + selectedAcc);
for (Object object : accountList) {
selectedAccount = (Account) object;
if (selectedAccount.getAccNumber() == selectedAcc) {
flag = true;
break;
} else {
flag = false;
}
}
if (!flag) {
System.out.println("Account doesn't exists.");
}
if (accountList.size() == 0) {
System.out.println("Zero account exists.");
}
break;
case "del":
// close account
System.out
.println("Enter account number for further operations : ");
int selectedAcc1 = scan.nextInt();
System.out.println("Selected account : " + selectedAcc1);
Iterator<Account> iterator = accountList.iterator();
while (iterator.hasNext()) {
selectedAccount = (Account) iterator.next();
if (selectedAccount.getAccNumber() == selectedAcc1) {
iterator.remove();
flag = true;
break;
}
}
if (!flag) {
System.out.println("Account doesn't exists.");
}
System.out.println("Account " + selectedAcc1 + " closed.");
break;
case "dp":
// Deposit amount
System.out.println("Enter amount to deposit : ");
amount = scan.nextDouble();
if (amount <= 0) {
System.out
.println("You must deposit an amount greater than 0.");
} else {
if (flag) {
selectedAccount.deposit(amount);
System.out.println("You have deposited " + amount
+ ". Total balance : "
+ (selectedAccount.getBalance()));
} else {
System.out.println("Please select account number.");
}
}
break;
case "wi":
// Withdraw amount
System.out.println("Enter amount to be withdrawn: ");
amount = scan.nextDouble();
if (amount > account.getBalance() && amount <= 0) {
System.out.println("You can't withdraw that amount!");
} else if (amount <= selectedAccount.getBalance()) {
if (flag) {
selectedAccount.withdraw(amount);
System.out.println("You have withdraw : " + amount
+ " NewBalance : "
+ selectedAccount.getBalance());
} else {
System.out.println("Please select account number.");
}
}
break;
case "bal":
// check balance in selected account
if (flag) {
System.out.println("Your current account balance : "
+ selectedAccount.getBalance());
} else {
System.out.println("Please select account number.");
}
break;
case "exit":
default:
// quit
System.out.println("Thank You. Visit Again!");
flag = false;
input.close();
scan.close();
System.exit(0);
break;
}
} // end of menu loop
}// end of main
} // end of class
I have tested this code & it is working fine.
Output :
Enter the option for the operation you need:
****************************************************
[ Options: new - New Account del - Delete Account ]
[ dp - Deposit wi - Withdraw bal - Check balance ]
[ se - Select Account exit - Quit ]
****************************************************
> new
Enter account number : 101
Enter initial balance: 10000
Current account: 101 Balance 10000
> new
Enter account number : 102
Enter initial balance: 25000
Current account: 102 Balance 25000
> se
Enter account number for further operations : 103
Selected account : 103
Account doesn't exists.
> se
Enter account number for further operations : 101
Selected account : 101
> bal
Your current account balance : 10000.0
> dp
Enter amount to deposit : 2500
You have deposited 2500.0. Total balance : 12500.0
> wi
Enter amount to be withdrawn: 500
You have withdraw : 500.0 NewBalance : 12000.0
> se
Enter account number for further operations : 102
Selected account : 102
> bal
Your current account balance : 25000.0
> del
Enter account number for further operations : 101
Selected account : 101
Account 101 closed.
> se
Enter account number for further operations : 101
Selected account : 101
Account doesn't exists.
> exit
Thank You. Visit Again!