How to do Upcasting of an Object ?

[Shyam Singh]

Code -->


class emp {

emp() { }
}

class manager extends emp{

manager() { }

public static void main(String []a) {
manager m=new manager();

m=(manager)new emp(); // Run Time Class cast error


if(m instanceof emp)
System.out.println(" M is of Emp Class");
else
System.out.println(" M is of Manager Class");
}
}
class upcasting extends manager {
}


Error -->

java.lang.ClassCastException
at manager.main(Empty.java:14)
Exception in thread "main" 

[Norm]

The problem is that emp is not a manager. Not all employees are managers.
It's the other way around -> manager is an emp. All managers are employees.

[Fubarable]

you can't do this:

m=(manager)new emp();

nor would you want to.

[hardwired]

Casting is discussed on the page Inheritance.

class manager extends emp {
    manager() { }

    public static void main(String[] a) {
        manager m=new manager();

        System.out.println("m = " + m.getClass().getName());
        System.out.println("superclass of m = " +
                            m.getClass().getSuperclass().getName());

        emp anEmp = new emp();

        //manager misMatch = new emp();

        emp anotherManager = new manager();

        // This works but is not necessary.
        emp castUp = (emp)m;

        emp upCast = m;
        System.out.println("upCast = " + upCast.getClass().getName());
        System.out.printf("upCast instanceof manager = %b%n",
                           upCast instanceof manager);
        System.out.printf("upCast instanceof emp = %b%n",
                           upCast instanceof emp);

        if(m instanceof emp) 
            System.out.println(" M is of Emp Class");
        else 
            System.out.println(" M is of Manager Class");
    }
}

class emp {
    emp() { }
}