I am trying to solve a problem about inheritance. It is about making a base account and then make a debit card that inherits from the base account.
The problem is that I do not know how to keep the value of the method in the child class.
Here is my code:
public class BaseAccount {
private double opening;
private double currentAmount = 0.0;
private double amount;
public BaseAccount(double opening, double currentAmount, double amount) {
this.opening = opening;
this.currentAmount = currentAmount;
this.amount = amount;
}
public double getOpening() {
return opening;
}
public void setOpening(double opening) {
this.opening = opening;
}
public double getCurrentAmount() {
return currentAmount;
}
public void setCurrentAmount(double currentAmount) {
this.currentAmount = currentAmount;
}
public double getAmount() {
return amount;
}
public void setAmount(double amount) {
this.amount = amount;
}
public String opening(double opening) {
this.opening = opening;
this.currentAmount = currentAmount opening;
return "This account has been openend with " this.opening;
}
public String deposit(double amount) {
this.currentAmount = amount;
return "Depositing " amount;
}
public String balance() {
return "Balance: " currentAmount;
}
}
public class DebitCard extends BaseAccount{
public DebitCard(double opening, double currentAmount, double amount) {
super(opening, currentAmount, amount);
}
public String withdraw(double amount) {
double currentAmount = getCurrentAmount() - amount;
return amount " have been retired. \nBalance: " currentAmount;
}
}
public class Inheritance {
public static void main(String[] args) {
BaseAccount base1 = new BaseAccount(0,0,0);
System.out.println(base1.opening(500));
System.out.println(base1.deposit(22.22));
System.out.println(base1.balance());
DebitCard debit1 = new DebitCard(0,0,0);
System.out.println(debit1.opening(400));
System.out.println(debit1.deposit(33.33));
System.out.println(debit1.balance());
System.out.println(debit1.withdraw(33.33));
System.out.println(debit1.balance());
}
}
Run:
This account has been opened with 500.0
Depositing 22.22
Balance: 522.22
This account has been opened with 400.0
Depositing 33.33
Balance: 433.33
33.33 have been retired.
Balance: 400.0
Balance: 433.33
I do not understand why the balance at the ends ignores the change I made in the retire function of the child class. I know I have to do something with the getters and setters but I do not know what exactly.
CodePudding user response：
double currentAmount = getCurrentAmount() - amount;
This statement does not change the value of the currentAmount field: it creates a new currnetAmount local variable. If you want to be able to modify the currentAmount field then it cannot be private.
Try adding setCurrentAmount(currentAmount); to the withdraw method.
Also, the amount field is unused.
Edit:
public String withdraw(double amount) {
double currentAmount = getCurrentAmount() - amount;
setCurrentAmount(currentAmount);
return amount " have been retired. \nBalance: " currentAmount;
}