please help

[srilatha annepu]

class Trebble{
int i = 99;
}
class Base extends Trebble{
int i =100;
}
public class Central extends Base{
public static void main(String argv[]){
Central c = new Central();
c.wynyard();
}
public void wynyard(){
Trebble t = new Central();
Base b = (Base) t;
System.out.println(b.i);
}

}



class Base {}
class Sub extends Base {}
class Sub2 extends Base {}
public class test extends Sub{
public static void main(String argv[]){
Base b=new Base();
Sub s=(Sub) b;
}
}
(one compiles fine but other gets a runtime error)
can u please explain these two programs output.thanks

[wise owen]

    
class Trebble{
int i = 99;
}
class Base extends Trebble{
int i =100;
}
public class Central extends Base{
public static void main(String argv[]){
Central c = new Central();
c.wynyard();
}
public void wynyard(){
Trebble t = new Central();
Base b = (Base) t;
System.out.println(b.i);
}
 
}

output is 100.

Instance variables binded at compile time depending on the type of the reference variable and not on the object.
At compile time, b has Base type.

    
 
class Base {}
class Sub extends Base {}
class Sub2 extends Base {}
public class test extends Sub{
public static void main(String argv[]){
Base b=new Base();
Sub s=(Sub) b;
}
}

b is a instance of Base class. You can not cast it to its subclass.

[srilatha annepu]

thank you