Variable in derived class may have not been initialized (using constructors)

Question

I am new to Java Programming and i am trying to experiment with inheritance and constructors.

My parent class:

class user{

    private String name;
    private float balance;
    private int accno;
    private int passw;

    public String getName()
    {
        return name;
    }
    .
    .
    .
    //getters and setters for the remaining variables.
}

My derived class:

class userFunct extends user
{

    userFunct(int accno,String name,int passw,float bal){                   //parametrized constructor

        super.setPassw(passw);
        super.setName(name);
        super.setAccno(accno);
        super.setBalance(bal);
    }

In my main program, i do this:

public static void main()
{
    userFunct obj=new userFunct(accno,name,passw,bal);  //Creating an object userFunct
    .
    .
    .
}

I get an error saying

variable accno may not have been initialized

Now since this had lots of lines i wrote a smaller piece of code

import java.util.*;
import java.io.*;

class a{
    public int x;

}

class b extends a{
    /*static*/ void pri(a obj)
    {
        System.out.println("Class b"+obj.x);
    }
    b(int num)
    {
        super.x=num;
    }
}


public class Main
{
    int num=9;
    public static void main(String[] args) {

        b objb=new b(9);
        objb.pri(objb);
    }
}

And this works fine, with proper outputs. I cannot spot the mistake when i compare the two codes.

I don't know if this is some silly mistake on my side or if there is some underlying concept that i have failed to understand. Either ways, I would like to know what is happening here

Answer 1

The difference between two code you shared in user class you declared all variable as private and not initialised. In your class a you declared variable as public.

So assign a initial value to all variable an enjoy

class user {
String name = "";
float balance = 0.0f;
int accno = 0;
int passw = 0;

public String getName()
{
    return name;
}

public void setName(String name) {
    this.name = name;
}

public float getBalance() {
    return balance;
}

public void setBalance(float balance) {
    this.balance = balance;
}

public int getAccno() {
    return accno;
}

public void setAccno(int accno) {
    this.accno = accno;
}

public int getPassw() {
    return passw;
}

public void setPassw(int passw) {
    this.passw = passw;
}

}