Develop Reference

How to store and modify balance on account:

I have a small acount in which to deposit, withdrawl, view balance, and exit. Everything runs perfectly however I would like the balance to ajust according to what method I do (withdrawal, deposit, etc.) I started with joptionpane but had the same problem and thought I should just start over. Anyone point me in the right direction?
Main file:
import java.util.Scanner;
public class Bank1
{
public static void main(String[] args)
{
HomeBank obj1 = new HomeBank();
Scanner keyboard = new Scanner(System.in);
String option;
char object;
System.out.println("This is your home banking account" + "\n");
do
{
System.out.println("What would you like to do today?"+ "\n" +
"\nSelect the following: " +
"\n'B' To View Balance." +
"\n'D' To Deposit" +
"\n'W' To Withdrawal" +
"\n'E' To Exit");
System.out.print("Your selection: ");
option = keyboard.next().toUpperCase();
object = option.charAt(0);
System.out.print("\n");
System.out.println("you entered: " +object+ "\n");
if(object =='D')
obj1.deposit();
else if(object =='W')
obj1.withdrawal();
else if(object =='B')
obj1.balance();
else
System.out.println("**Invalid input**" +
"\n Please try again");
} while(object !='E');
System.out.println("The End");
}
}
Class:
import java.util.InputMismatchException;
import java.util.Scanner;
public class HomeBank
{
private double withdrawal, deposit, balance;
public HomeBank()
{
balance = 100;
withdrawal = 50;
deposit = 150;
}
public HomeBank(double bal, double with, double de)
{
balance = bal;
withdrawal = with;
deposit = de;
}
public static void balance()
{
double balance = 250.00d;
System.out.println("You have $" + balance+"dollars");
}
public static void deposit()
{
Scanner keyboard = new Scanner(System.in);
double deposit = 0.00d;
double balance = 250.00d;
boolean goodput =true;
do
{
try
{
System.out.print("How much would you like to deposit today? :");
deposit = keyboard.nextDouble();
if(deposit > 0.00)
{
System.out.println("you entered $" +deposit+" dollars");
System.out.println("you now have $" + (deposit + balance)+" dollars");
goodput = false;
}
else
{
System.out.println("\n**Error**\nYou cannot deposit a "
+ "negative amount\n");
System.out.println("Please try again\n");
goodput = true;
}
}
catch (InputMismatchException x)
{
System.out.println("I'm sorry but that is an invalid input" +
"\nYou will be redirected to the main menu shortly..."+
"\n");
goodput = false;
}
} while (goodput == true);
}
public static void withdrawal()
{
Scanner keyboard = new Scanner(System.in);
double withdrawal = 0.00d;
double balance = 250.00d;
boolean goodput = true;
do
{
try
{
System.out.println("How much would you like to withdrawal?");
withdrawal = keyboard.nextDouble();
if (withdrawal < 0 || withdrawal > balance)
{
System.out.println("You have either entered a negative number"
+ "or trying to withdrawal more than is in your account");
System.out.println("You cannot withdrawal more than $"+balance);
System.out.println("Please try again");
goodput = true;
}
else
{
System.out.println("You now have $" +(balance-withdrawal)+ "dollars");
System.out.println("Thank you for choosing HomeBank\n"
+ "\nYou will be redirected to the main menu\n");
goodput =false;
}
}
catch (InputMismatchException x)
{
System.out.println("I'm sorry but that is an invalid input" +
"\nYou will be redirected to the main menu shortly..."+
"\n");
goodput = false;
}
} while (goodput == true);
}
}

The issue is how you are updating the values. In your methods, you have something that goes like the following:
double deposit = 0.00d;
double balance = 250.00d;
In there, notice how you are putting the double keyword before the variable. By doing that, you are telling Java to create a new variable named deposit and balance in the local scope.
If you want to modify the fields named deposit and balance, you would definitely have to remove the double keyword before them, and optionally put this. in front of the variable. It would look something like the following:
deposit = 0.00d;
balance = 250.00d;
Or
this.deposit = 0.00d;
this.balance = 250.00d;
You would replace all instances of the variables withdraw, balance, and deposit like that, but only the declaration.
The reason you don't need to specify the type is because you already define it in the field declaration. Therefore when you again define it in the method, you are saying to create a new variable with that name and type in the current scope.
Edit:
As Suyash Limaye said, you will have to remove the static keywords from the methods. Having the static keywords prevents the methods from being able to access the non-static fields, which will cause conflicts.

NetBeans : Trying to create a class file to work with another program

Having trouble compiling these two files to run together.
I get a "can't find or load main class" error or a "erroneous tree" error.
Never asked for help on here before, hope this works :)
package savingsaccount;
import java.util.Scanner;
public class SavingsAccount
{
public static void main(String[] args)
{
double begginingBalance, deposit, withdraw;
int months;
double monthlyRate;
double plus = 0.0;
double minus = 0.0;
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter the balance at beggining of " +
"accounting period.");
begginingBalance = keyboard.nextDouble();
System.out.println("Please enter number of months in current " +
"accounting period.");
months = keyboard.nextInt();
System.out.println("Enter the annual interest rate.");
monthlyRate = keyboard.nextDouble();
a7main accounting = new a7main();
for(int month = 1; month<=months; month++)
{
System.out.println("Enter the amount of deposits for month " +
month + " : ");
plus = keyboard.nextDouble();
accounting.deposits(plus);
System.out.println("Enter the amount of withdrawals for" +
" month " + month + ": ");
minus = keyboard.nextDouble();
accounting.withdrawals(minus);
accounting.interest(monthlyRate);
}
System.out.println("The account balance is: " +
accounting.getBalance());
System.out.println("The total amount of deposits is:" + plus);
System.out.println("The total amount of withdrwals is: " + minus);
System.out.println("The earned interest is: " +
accounting.getRate());
}
}
HERE IS THE CLASS FILE
I am trying to use the methods in this file to calculate and hold the values from the other file.
public class a7main
{
private double totalBalance;
private double interestRate;
public a7main(double balance,double rate)
{
totalBalance = balance;
interestRate = rate;
}
public void deposits(double deposit)
{
totalBalance = totalBalance+deposit;
}
public void withdrawals(double withdraw)
{
totalBalance = totalBalance-withdraw;
}
public void interest(double rate)
{
interestRate = totalBalance*rate;
}
public double getBalance()
{
return totalBalance;
}
public double getRate()
{
return interestRate;
}
}

#Alex Goad -
Add package name in a7main class
You have created parameterized constructor and no default constructor.
a7main accounting = new a7main();
The above line will look for default constructor like
public a7main(){
}

If statement is being missed in Bank Account Class?

I am having some issues with the following syntax.
I am currently learning Java and have been going through a past exam paper to help build my knowledge of Java.
Here is the question:
Write a class Account that has instance variables for the account number and current balance of the account. Implement a constructor and methods getAccountNumber(), getBalance(), debit(double amount) and credit(double amount). In your implementations of debit and credit, check that the specified amount is positive and that an overdraft would not be caused in the debit method. Return false in these cases. Otherwise, update the balance.
I have attempted to do this HOWEVER, I have not implemented the boolean functions for debit and credit methods. I just wanted to build the program first and attempt to get it working. I was going to look at this after as I was not sure how to return true or false whilst also trying to return an amount from the said methods.
Please forgive any errors in my code as I am still learning Java.
I can run my code, but when I enter deposit it does not seem to work correctly and I would appreciate any pointers here please.
Here is my code:
import java.util.*;
public class Account {
private int accountNumber;
private static double currentBalance;
private static double debit;
// ***** CONSTRUCTOR *****//
public Account(double currentBalance, int accountNumber) {
accountNumber = 12345;
currentBalance = 10000.00;
}
public int getAccountNumber(int accountNumber) {
this.accountNumber = accountNumber;
return accountNumber;
}
public double getcurrentBalance(double currentBalance) {
this.currentBalance = currentBalance;
return currentBalance;
}
public static double debit(double currentBalance, double amount) {
currentBalance -= amount;
return currentBalance;
}
public static double credit(double currentBalance, double amount) {
currentBalance += amount;
return currentBalance;
}
public static void main(String [] args){
String withdraw = "Withdraw";
String deposit = "Deposit";
double amount;
Scanner in = new Scanner(System.in);
System.out.println("Are you withdrawing or depositing? ");
String userInput = in.nextLine();
if(userInput == withdraw)
System.out.println("Enter amount to withdraw: ");
amount = in.nextDouble();
if(amount > currentBalance)
System.out.println("You have exceeded your amount.");
debit(currentBalance, amount);
System.out.println("Your new balance is: " + currentBalance);
if (userInput == deposit)
System.out.println("Enter amount to deposit: ");
amount = in.nextDouble();
credit(currentBalance, amount);
System.out.println("Your new balance is: " + currentBalance);
}
}
Again please forgive any errors in my code. I am still learning its syntax.

In the if-statement if(userInput == withdraw) you are attempting to compare String objects.
In Java to compare String objects the equals method is used instead of the comparison operator ==
if(userInput.equals(withdraw))
There are several instances in the code that compares String objects using == change these to use equals.
Also when using conditional blocks it is best to surround the block with braces {}
if(true){
}

You don't use brackets so only the first line after your if-statement gets executed. Also, String's should be compared using .equals(otherString). Like this:
if(userInput.equals(withdraw))
System.out.println("Enter amount to withdraw: "); //Only executed if userInput == withdraw
amount = in.nextDouble(); //Always executed
if(userInput.equals(withdraw)) {
System.out.println("Enter amount to withdraw: ");
amount = in.nextDouble();
//All executed
}
Do this:
if(userInput.equals(withdraw)) {
System.out.println("Enter amount to withdraw: ");
amount = in.nextDouble();
if(amount > currentBalance)
System.out.println("You have exceeded your amount.");
debit(currentBalance, amount);
System.out.println("Your new balance is: " + currentBalance);
}
if (userInput.equals(deposit)) {
System.out.println("Enter amount to deposit: ");
amount = in.nextDouble();
credit(currentBalance, amount);
System.out.println("Your new balance is: " + currentBalance);
}
Note that if your amount to withdraw exceeds your current balance, you will get a 'warning message' but your withdrawal will continue. Thus you'll end up with a negative sum of money. If you don't want to do this, you have to change it accordingly. But, this way it shows how the use of brackets (or not using them) has different effects.

if (userInput == deposit)
should be
if (userInput.equals(deposit))
Same for withdrawal.

On these methods:
public static double debit(double currentBalance, double amount) {
currentBalance -= amount;
return currentBalance;
}
public static double credit(double currentBalance, double amount) {
currentBalance += amount;
return currentBalance;
}
The inputs to the functions really shouldn't include the current balance, the object already knows what the current balance is (its being held in the objects currentBalance field, which as has been pointed out shouldn't be static).
Imagine a real cash machine that behaved like this:
Whats my current balance:
£100
CreditAccount("I promise my current balance is £1 Million, it really is", £10):
Balance:£1,000,010
Edit: Include code to behave like this
import java.util.*;
public class Account {
private int accountNumber;
private double currentBalance; //balance kept track of internally
// ***** CONSTRUCTOR *****//
public Account(int accountNumber, double currentBalance) {
this.accountNumber = accountNumber;
this.currentBalance = currentBalance;
}
public int getAccountNumber() {
return accountNumber;
}
public double getcurrentBalance() {
return currentBalance;
}
public boolean debit(double amount) {
//we just refer to the objects fields and they are changed
if (currentBalance<amount){
return false; //transaction rejected
}else{
currentBalance -= amount;
return true;
//transaction approaved and occured
}
//Note how I directly change currentBalance, there is no need to have it as either an input or an output
}
public void credit( double amount) {
//credits will always go through, no need for return boolean
currentBalance += amount;
//Note how I directly change currentBalance, there is no need to have it as either an input or an output
}
public static void main(String [] args){
Account acc=new Account(1234,1000);
acc.credit(100);
System.out.println("Current ballance is " + acc.getcurrentBalance());
boolean success=acc.debit(900); //there is enough funds, will succeed
System.out.println("Current ballance is " + acc.getcurrentBalance());
System.out.println("Transaction succeeded: " + success);
success=acc.debit(900); //will fail as not enough funds
System.out.println("Current ballance is " + acc.getcurrentBalance());
System.out.println("Transaction succeeded: " + success);
}
}
I've not bothered using the typed input because you seem to have the hang of that

Without '{' and '}' the first line after an if statement only gets executed as part of that statement. Also, your if (userInput == deposit) block isn't correctly indented, it shouldn't be under the if (userInput == withdraw). And string comparisons should be done using userInput.equals(withdraw)

For the debit and credit methods:
public static boolean debit(double currentBalance, double amount) {
currentBalance -= amount;
if<currentBalance < 0){
return false
}
return true;
}
public static boolean credit(double currentBalance, double amount) {
currentBalance += amount;
if<currentBalance > 0){
return false
}
return true;
}
Now I think I have the boolean values mixed up. The description is a little bit unclear on what to return for each method.

Use equals() method instead == which compares the equality of Objetcs rather values
import java.util.*;
public class Account{
private int accountNumber;
private static double currentBalance;
private static double debit;
// ***** CONSTRUCTOR *****//
public Account(double currentBalance, int accountNumber) {
accountNumber = 12345;
currentBalance = 10000.00;
}
public int getAccountNumber(int accountNumber) {
this.accountNumber = accountNumber;
return accountNumber;
}
public double getcurrentBalance(double currentBalance) {
this.currentBalance = currentBalance;
return currentBalance;
}
public static double debit(double currentBalance, double amount) {
currentBalance -= amount;
return currentBalance;
}
public static double credit(double currentBalance, double amount) {
currentBalance += amount;
return currentBalance;
}
public static void main(String [] args){
String withdraw = "Withdraw";
String deposit = "Deposit";
double amount;
Scanner in = new Scanner(System.in);
System.out.println("Are you withdrawing or depositing? ");
String userInput = in.nextLine();
if(userInput.equals(withdraw))
System.out.println("Enter amount to withdraw: ");
amount = in.nextDouble();
if(amount > currentBalance)
System.out.println("You have exceeded your amount.");
debit(currentBalance, amount);
System.out.println("Your new balance is: " + currentBalance);
if (userInput .equals(deposit))
System.out.println("Enter amount to deposit: ");
amount = in.nextDouble();
credit(currentBalance, amount);
System.out.println("Your new balance is: " + currentBalance);
}
}

bank account client in java with multiple classes

I am trying to make a bank account program, but I cannot figure out how to get all my variables visible to every class that I have, or how to make the withdrawal and deposit methods of my code visible. Can anyone look at my code and tell me what is wrong? I only want input and output in the client class.
Thanks
Client Class
public class Client {
public static void main(String args[]) {
Scanner input = new Scanner(System.in);
System.out.println("Enter your Name: ");
String cusName = input.nextLine();
System.out.println("Enter Account Type: ");
String type = input.next();
System.out.println("Enter Initial Balance: ");
int bal = input.nextInt();
BankAccount b1 = new BankAccount(cusName, num, type, bal);
int menu;
System.out.println("Menu");
System.out.println("1. Deposit Amount");
System.out.println("2. Withdraw Amount");
System.out.println("3. Display Information");
System.out.println("4. Exit");
boolean quit = false;
do {
System.out.print("Please enter your choice: ");
menu = input.nextInt();
switch (menu) {
case 1:
b1.deposit();
break;
case 2:
b1.withdraw();
System.out.println("Current Account Balance=" + Balance);
System.out.print("Enter withdrawal amount:");
amount = input.nextInt();
break;
case 3:
b1.display();
break;
case 4:
quit = true;
break;
}
} while (!quit);
}
}
Money Class
public class Money
{
static int accountNumber, Balance, amount;
Scanner input = new Scanner(System.in);
static String name, actype;
public int deposit() {
System.out.print("Enter depost amount:");
amount = input.nextInt();
if (amount < 0) {
System.out.println("Invalid");
return 1;
}
Balance = Balance + amount;
return 0;
}
int withdraw() {
if (Balance < amount) {
System.out.println("Not enough funds.");
return 1;
}
if (amount < 0) {
System.out.println("Invalid");
return 1;
}
Balance = Balance - amount;
return 0;
}
}
BankAccount Class
class BankAccount {
Scanner input = new Scanner(System.in);
static String name, actype;
static int bal, amt;
Random randomGenerator = new Random();
int accNo = randomGenerator.nextInt(100);
BankAccount(String name, int accNo, String actype, int bal) {
this.name = name;
this.accNo = accNo;
this.actype = actype;
this.bal = bal;
}
void display() {
System.out.println("Name:" + name);
System.out.println("Account No:" + accNo);
System.out.println("Balance:" + bal);
}
void dbal() {
System.out.println("Balance:" + bal);
}
}

Add Money to your BankAccount and create a getter method as:
class BankAccount {
Scanner input = new Scanner(System.in);
static String name, actype;
static int bal, amt;
Random randomGenerator = new Random();
int accNo = randomGenerator.nextInt(100);
Money money;
BankAccount(String name, int accNo, String actype, int bal) {
this.name = name;
this.accNo = accNo;
this.actype = actype;
this.bal = bal;
this.money = new Money();
}
public Money getMoney(){
return this.money;
}
.....
}
Use bankaccount.getMoney() to invoke deposit and withdraw as :
b1.getMoney().deposit();
b1.getMoney().withdraw();
In addition, I would advice to make the Money class attributes e.g. amount, accntType... non-static and set through through a constructor. Static variables are associated with class definition and hence you won't be abl to maintain them per Bank Account.

I'm not going to answer this question for you. Instead, I'm going to recommend that you read a bit more about Java programming concepts that will explain it to you, by default.
Here is one on encapsulation, which is the main concept that you're asking about
This is a great book on how to write code well, including things like keeping methods short
In particular, your main method should be broken into smaller pieces
Here's a stack overflow question that talks about it if you don't want to buy the book.
If you don't want to read any of these links, #YogendraSingh answered this question really well, use that answer.

Attributes to an object shouldn't be static, for example your "name, actype, bal and amt". Also I think your money class should exist and those methods could be in a bank account (you deposit/withdraw from a bank account).

Bank Account Program Issue

For my Java class, we need to make a bank account that has the methods of withdrawing, depositing money, and displaying current balance. In the Tester class, I want to make it ask for the name, the balance, then allow you to choose 1, 2, or 3. Then it repeats the option you choose until you say type "n". The problem is that running this code causes it to say after you deposit money "You deposited (amount of money deposited) in the account (name of account). Your new balance is (this)." The part where it says "this" is the exact same of the amount of money deposited. In other words, it doesn't add it, it just makes the new balance the same as the deposit, regardless of how much was in before. Any help? Thanks.
import java.io.*;
import java.util.*;
public class BankAccount
{
public BankAccount(double b, String n)
{
double balance = b;
String name = n;
}
public void deposit(double d)
{
balance += d;
}
public void withdraw(double w)
{
balance -= w;
}
public String nickname()
{
System.out.print("Enter a new name: ");
Scanner kbIn = new Scanner(System.in);
String n = kbIn.nextLine();
return n;
}
double balance;
String name;
}
And the tester class:
import java.io.*;
import java.util.*;
public class Tester
{
public static void main(String args[])
{
Scanner kbInLine = new Scanner(System.in);
Scanner kbIn = new Scanner(System.in);
System.out.print("Enter your name: ");
String name = kbInLine.nextLine();
System.out.print("Please enter balance: $");
double balance = kbIn.nextDouble();
BankAccount myAccount = new BankAccount(balance, name);
String proceed = "y";
while(proceed.equalsIgnoreCase("y"))
{
System.out.println("\nPlease pick a number. Would you like to...\n\t 1. Deposit\n\t 2. Withdraw\n\t 3. Print Balance\n");
int choice = kbIn.nextInt();
switch(choice)
{
case 1:
System.out.print("How much would you like to deposit?\n\t$");
double deposit = kbIn.nextDouble();
myAccount.deposit(deposit);
System.out.println("You have deposited $" + deposit + " into the account of " + name + ". The new balance is: " + myAccount.balance);
break;
case 2:
System.out.print("How much would you like to withdraw?\n\t$");
double withdraw = kbIn.nextDouble();
if(myAccount.balance - withdraw > 0)
{
myAccount.withdraw(withdraw);
System.out.println("You have withdrawn $" + withdraw + " from the account of " + name + ". The new balance is: " + myAccount.balance);
}
else
{
System.out.println("Sorry, you have insufficient funds for this operation. Your existing balance is $" + myAccount.balance);
}
break;
case 3:
System.out.print("The balance in the account of " + name + " is $" + myAccount.balance);
break;
}
System.out.print("\nWould you like to do another transaction? (Y/N)");
proceed = kbIn.next();
}
System.out.println("\nThank you for banking with us. Have a good day!");
}
}
What's really wierd is that I did a project before this one (it's actually a simplified version) where it deposits and then withdraws a predetermined, coded amount, then outputs the new bank balance, and it does it fine. But the code for BankBalance is the same. Here's the code for those.
BankAccount class is:
public class BankAccount
{
public BankAccount(String nm, double amt) // Constructor
{
name = nm;
balance = amt;
}
public void deposit(double d) // Sets up deposit object as balance += d
{
balance += d;
}
public void withdraw(double w) // Sets up withdraw object as balance -= w
{
balance -= w;
}
public double balance;
public String name;
}
And the Tester class is:
import java.io.*;
import java.util.*;
public class Tester
{
public static void main(String args[])
{
Scanner kbIn = new Scanner(System.in);
System.out.print("Enter your name:");
String name = kbIn.nextLine();
System.out.print("Enter the balance:");
double balance = kbIn.nextDouble();
BankAccount myAccount = new BankAccount(name, balance);
myAccount.deposit(505.22);
System.out.println(myAccount.balance);
myAccount.withdraw(100.00);
System.out.println("The " + myAccount.name + " account balance is, $" + myAccount.balance);
}
}

You're not actually initialising your balance member variable here:
public BankAccount(double b, String n)
{
double balance = b;
This creates a new local variable called balance, to which you assign the value of b. The member variable balance will remain 0 (the default) after this constructor is run.

public BankAccount(double b, String n)
{
double balance = b;
String name = n;
}
--->
public BankAccount(double b, String n)
{
this.balance = b;
this.name = n;
}

Or you can declare balance as static (data class field), and the methods that use this variable as static too.