Question

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);
    }
}

Answer 1

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.