Help me to get the output.............I Know the answer but tell me how you got that?

[Manoj Mani]

class A{
int a=10;
A()
{call();}
void call(){
System.out.println("a="+a);
}
}
class B extends A
{
int b=16;
B(){
call();
}
void call()
{
System.out.println("b="+b);
}
public static void main(String args[])
{
B ob = new B();
}
}

[Chandra Bhatt]

Hi Manoj,

class A{
int a=10;
A() {
    call();
}
void call(){
    System.out.println("a="+a);
}
}
class B extends A {
    int b=16;
    B(){
        call();
    }
void call() {
    System.out.println("b="+b);
}
public static void main(String args[]) {
    B ob = new B();
}
}

Output:
b=0
b=16

Facts to think about:
1- If method is overridden, which method to call at run time
2- Order of initialization
3- Constructor call
4- Until constructor of the the parent class completes, subclass member variables are not initialized.
5- Sub class object is created, from the parent class constructor you make call to the method that is overridden in the subclass, subclass version is selected at run time.
6- When parent class constructor runs value of "b" gets its default (0 for integer member variable) and, after that b gets its value 16 before the constructor of the subclass executes.


Think, you will get the answer

Thanks and Regards,
cmbhatt
[ April 07, 2007: Message edited by: Chandra Bhatt ]

[Arad Chear]

oops how its print b=0 ??

i thought super constructor will call its method , but it doesn't

even if he call sub method how its become 0 an we assign 16 to it ?

[Remko Strating]

The super constructer within class A will call it's method, but because of inheritence it will call the method of class B which will print the value of b within class B,

Because the constructor of class B has not run the default value will be displayed and this is 0.

The following code will make this clear

   
    class A{
    int a=10;
    A() {
        call();
    }
    void call(){
        System.out.println("a="+a);
    }
    }
    class B extends A {
        int b=16;
        B(){
            call();
        }
    void call() {
    System.out.println("Method in B"); 
        System.out.println("b="+b);
    }
    public static void main(String args[]) {
        B ob = new B();
    }
    }

[Manoj Mani]

Good answer..................Keep replying to my doubts....Have a nice day..