please say what is wrong in code and how it will be corrected in class definitions

Question

class Point

{ private int x, y;

public Point (int x, int y)

{this.x = x; this.y = y;}

public int getX ( ) { return x; }

public int getY ( ) { return y; }

}

class ScaledPoint extends Point

{ private int c;

public ScaledPoint (int x, int y, int c)

{ this.x = x; this.y = y; this.c = c;}

public void getC ( ) { return c; }

}

Answer 1

1. Firstly we can't access the private data variable of parent class in chlid class.

2. While assign the values of variable of parent class use super()

Corrected Code below:

class Point

{
    public int x, y;

    public Point (int x, int y)
    {
        this.x = x;
        this.y = y;
    
    }
    
    public int getX ( ) { return x; }
    
    public int getY ( ) { return y; }

}
 class ScaledPoint extends Point

{
    private int c;

    public ScaledPoint (int x, int y, int c)
    {
        super(x,y);
        this.c = c;
        
    }
    
    public int getC ( ) { return c; }

}

Answer 2

There were various problems with your code:

• In Java the this pointer cannot be used in the constructor to access members. Since it cannot be used, you need to have different name for the arguments and the member variables. (I used the _ to prefix member variables.)
• To set members in the base class, you better call the constructor of the base class from the constructor of the derived class. For this use the super() to invoke the base constructor.
• Your getC() method had the wrong (void) return type. It should be int.
• You need a main() method in your code

Here's the fixed code:

class Point
{
    private int _x, _y;

    public Point(int x, int y)
    {
        _x = x;
        _y = y;
    }

    public int getX() { return _x; }
    public int getY() { return _y; }
}

class ScaledPoint extends Point
{
    private int _c;

    public ScaledPoint(int x, int y, int c)
    {
        super(x, y);
        _c = c;
    }

    public int getC() { return _c; }
}

public class Main
{
    public static void main(String[] args)
    {
        ScaledPoint scaledPoint = new ScaledPoint(1, 2, 3);
    }
}

Comments

very prestigious