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Thread: Problem with OOP - Inheritance

  1. #1
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    Default Problem with OOP - Inheritance

    Basically I've made 4 classes, 1 main class, which 3 classes are then extended by. This is the main class file:

    public class Account
    {   
         private float balance;
     
        float getBalance()
        {
            return balance;
        }   
     
    }

    A class file that extends on this is:

    public class Second extends Account
    {
     
         private float balance;
     
        public Loan(float loanBalance)
        {
            balance = loanBalance;
        }
     
    }

    My main class file is:

    public class Main {
     
        public static void main(String[] args)
        {
           Second JoeLoan = new Second(2000);
           float f = JoeLoan.getBalance();
          System.out.println(f);
        }
    }

    This should ideally output 2000.0, however it outputs 0.0... any idea what could be wrong?
    Last edited by connex; December 14th, 2009 at 08:49 PM.


  2. #2
    Super Moderator copeg's Avatar
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    Default Re: Problem with OOP - Inheritance

    Look closely at your Second class. It overrides the parent class variable, and so the parent class function will return the balance variable available to it (which is never set, and so will be zero).

    public class Second extends Account
    {
     
         private float balance;//you are overriding the variable from the parent class. Best to omit this line
     
        public Loan(float loanBalance)//Should this be Second and not Loan?
        {
            balance = loanBalance;
        }
     
    }