Java issues with updating variables correctly

Question

I have the following Account class which is the super class of CurrentAccount. I am however having issues when I create an instance of each class. The currentAccount should take away 6 as a charge if the balance is below 100 but its taking away 3. I'm obviously missing a deceleration somewhere.

public class Account { private String name; private double balance; public double initDeposit; public double threshold = 100.00; public final double fee = 3.00; public Account(String name, double initDeposit) { this.balance = initDeposit; this.name = name; } public void deposit(double amount) { setBalance(amount); } public double getBalance() { return balance; } public void setBalance(double amount) { balance += amount; } public void withdraw(double amount) { if (getBalance() < 100 && getBalance() >= -50) { balance = balance - amount - fee; } else { balance = balance - amount; } } public String toString() { String s = "Name: " + name + "\n" + "Balance: " + balance; return s; } }

public class CurrentAccount extends Account { private String name; private double balance; public double initDeposit; public double threshold = 100.00; public final double fee = 6.00; public CurrentAccount(String name, double initDeposit) { super(name, initDeposit); } }

what do you mean by "taking away 6" and "taking away 3"? — Sam I am says Reinstate Monica
– Sam I am says Reinstate Monica, Commented Feb 10, 2014 at 20:08
Your seem to be trying to overide instance variables but are in fact shadowing them. You need to pass variables you want into the superclass constructor rather than redeclare them. — Boris the Spider
– Boris the Spider, Commented Feb 10, 2014 at 20:09

rgettman · Accepted Answer · 2014-02-10 20:09:42Z

In Java, instance variables do not replace or override the same named variable in a superclass. If you declare a same-named variable in a subclass, now you have two variables, not one. Just because you declared another fee in CurrentAccount doesn't mean the code in Account will use the fee in CurrentAccount -- it can't.

To apply the different behavior you need, declare a method called getFee() in Account returning a double that can be overridden in CurrentAccount to change the behavior.

In Account:

public double getFee() { return 3.00; }

In CurrentAccount:

@Override public double getFee() { return 6.00; }

Then call getFee() whenever you need to reference the fee, instead of referring to fee.

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