Encapsulation

Polymorphism

Abstraction

Inheritance

Adjusted price is : 45000

Adjusted price is : 15000

None of the above

Adjusted price is : 10000

Adjusted price is : 30000

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

On implementation of an interface, you must overload all of the methods

All of the above are true about interface in Java

An interface describes a set of methods that can be called on an object, not providing concrete implementation for the methods

Interface variables are by default, static, final and public

Interface methods are by default, abstract and public

In all the abstract class's direct, non-abstract sub classes

If you think all the above answers are wrong, select this option.

In at least one of the abstract class's direct, non-abstract sub classes

In all of the abstract class's descendant, non-abstract classes

Mackintosh obj = new Apple();

There is more than one invalid statement

Apple obj = new Orange();

Fruit obj = new Banana();

Apple obj = new GrannySmith();

Person

Student

Student

Person

public class B extends A

public class A inherits B

public class A extends B

public class B inherits A

Person

Student

Student

Person

Bad program design - it will cause a syntax error, as you can't declare the same field in two different classes.

Good program design, as having the variable in two different places ensures it will be correct.

Bad program design - it is an example of code duplication, which should be avoided.

Necessary, as both the Enrolment and Student classes need to access this information.