Overloading

[kumaran dhakshna]

hi rancher,

I tested this program i felt the result will be
The value of b is 200
In drived set
The value of b is 200

but the result is
The value of b is 200
In drived set
The value of b is 100


Why this is? Can anybody clear this.

 
public class Test
{
    int a;
    public Test()
    {
        a = 100;        
    }
    public void show()
    {
        System.out.println(this);
        System.out.println("the value of a is "+a);        
    }
    
    public void set(int a)
{
        System.out.println("In base set");
    this.a = a;
}
    
    public static void main(String args[])
    {
      Test t = new drived();
        t.show();
        t.set(t.a);
        t.show();
        
    }
}
 
class drived extends Test
{
    int a;
    public drived()
    {
        a = 200;        
    }
    public void show()
    {
        System.out.println("The value of b is " + a);
    }
    public void set(int a)
    {
        System.out.println("In drived set");
        this.a = a;
    }
} 
 

Thank in Advance
[ December 15, 2004: Message edited by: Barry Gaunt ]

[Surendra Kumar]

Hello Kumaran,

You can only override methods, not instance variables(t.a).

Cheers
Surendra

[Jugal Hans]

You can only override methods, not instance variables(t.a)

If that is the case then when t was created with constructor of the subclass it actually called the base class cosntructor ? is that correct interpretation ?

Thanks

[Mike Gershman]

In his case, there are two instance variables named "a". The one in Test is initialized to 100 by the Test constructor, which executes first. The one in drived is initialized to 200 by the drived constructor, which executes second.

However, the second "a" is changed to 100 by drived's set() method, which is called from main() in Test with Test's "a" as an argument.

Remember that the hidden first line of the drived constructor is "super();", which calls the Test constructor.

[Kunaal A Trehan]

Hi

Reason why u get 100 instead of 200 is that in case of variables,dynamic binding is not there.SO when u pass t.a.It sees t is defined as Test t=new Derived();.SO it picks value 100 belonging to Test not 200 belonging to Derived.

I hope it explains.

Rgds
Kunal