The code will not execute as there is a compile-time error.

Method in Lecturer

Person

Person

The code will not execute as there is a run-time error.

Person

Student

Student

Person

Lecturer lec = (Lecturer)objRef; 
lec.age = 21;

is an example of Downcasting

Person objRef = new Lecturer(); 
objRef.name = "Goo";

is an example of Upcasting

objRef.display(); 
lec.display();

outputs:

The code will not compile.

System.out.println(lec.name + "/" + lec.age);

outputs:

Goo/21

The code will not execute as there is a compile-time error.

Method in Lecturer

Person

Person

The code will not execute as there is a run-time error.

Person

Student

Student

Person

The ability of undefined data to be processed in at least one form

The ability for a data to be processed in more than one form

The ability for data to be defined in one form

The ability of data in a single form, to be reused by all subclasses

You can only downcast between classes and/or interfaces connected in a class/Interface hierarchy

It can be done without declaring a new variable

Select this option if you think none of the above are false

It's necessary when you want to invoke a method available in the object's class but not in its reference variable's class

The downcast must always be to the object's class

If you think all of the above are true, select this option

Their classes share a common ancestor class from which they are ultimately inherited

Each should produce a specialised effect appropriate to their class and therefore different to each other

To be invoked polymorphically, an object of their class's type must be referenced by a variable of an ancestor's type common to all of them

They must have identical signatures and therefore belong to separate classes

Lecturer lec = (Lecturer)objRef; 
lec.age = 21;

is an example of Downcasting

Person objRef = new Lecturer(); 
objRef.name = "Goo";

is an example of Upcasting

objRef.display(); 
lec.display();

outputs:

The code will not compile.

System.out.println(lec.name + "/" + lec.age);

outputs:

Goo/21

The code will not execute as there is a compile-time error.

Method in Lecturer

Person

Person

The code will not execute as there is a run-time error.