Polymorphism

Question 1

What is Runtime Polymorphism?

Answer 1

Runtime polymorphism is when the method to execute is determined at runtime based on the actual object type.

Question 2

What is another name for runtime polymorphism?

Answer 2

Dynamic polymorphism.

Question 3

Dynamic polymorphism.

Answer 3

Method overriding.

Question 4

When is method selection decided in runtime polymorphism?

Answer 4

At runtime, not at compile time.

Question 5

What determines which overridden method is called?

Answer 5

The actual object type, not the reference type.

Question 6

Example of runtime polymorphism?

Answer 6

Animal a = new Dog(); a.sound(); → Dog’s version runs.

Question 7

Why is runtime polymorphism useful?

Answer 7

It enables flexible and extensible designs where behavior varies by object type.

Question 8

Does runtime polymorphism require inheritance?

Answer 8

Yes. It requires a parent-child class relationship.

Question 9

Does runtime polymorphism work with static methods?

Answer 9

No. Static methods use compile-time binding.

Question 10

Is runtime polymorphism related to dynamic binding?

Answer 10

Yes. Runtime polymorphism is implemented through dynamic method dispatch.

Question 11

What is dynamic method dispatch?

Answer 11

JVM decides at runtime which overridden method implementation to call.

Question 12

Can private methods participate in runtime polymorphism?

Answer 12

No. Private methods cannot be overridden.

Question 13

Can final methods participate in runtime polymorphism?

Answer 13

No. Final methods cannot be overridden.

Question 14

What is the difference between compile-time and runtime polymorphism?

Answer 14

Compile-time uses overloading; runtime uses overriding.

Question 15

Can runtime polymorphism be achieved using data members in Java?

Answer 15

No. Runtime polymorphism applies only to methods, not variables.

Question 15

Key rule to remember?

Answer 15

Overriding + object type → runtime polymorphism.

Question 16

Why can’t fields support runtime polymorphism?

Answer 16

Because variable access is resolved at compile time based on reference type, not object type.

Question 17

What supports runtime polymorphism in Java?

Answer 17

Only overridden instance methods.

Question 18

What happens when subclass defines a field with same name as parent?

Answer 18

It results in variable hiding, not polymorphism.

Question 19

What is variable hiding?

Answer 19

It occurs when a subclass declares a field with the same name as a superclass field.

Question 20

Which value is accessed for hidden variables?

Answer 20

The value is chosen based on reference type, not object type.

Question 21

Example of variable hiding behavior?

Answer 21

Parent p = new Child(); System.out.println(p.x); prints Parent’s x.

Question 22

Can fields be overridden?

Answer 22

No. Fields cannot be overridden; only methods can.

Question 23

Why does Java restrict polymorphism to methods?

Answer 23

Because methods can be dynamically dispatched, while fields are statically resolved.

Question 24

Does method overriding affect field values?

Answer 24

No. Overriding only affects methods, not data members.

Question 25

Can static variables participate in polymorphism?

Answer 25

No. Static variables are resolved at compile time.

Question 26

Which concept enables runtime polymorphism?

Answer 26

Dynamic method dispatch.

Question 27

Key rule to remember?

Answer 27

Methods override; variables hide.

Question 28

What is the difference between static binding and dynamic binding in Java?

Answer 28

Static binding is resolved at compile time, while dynamic binding is resolved at runtime based on the actual object type.

Question 29

What is static binding?

Answer 29

It is method or variable resolution determined during compilation.

Question 30

What is dynamic binding?

Answer 30

It is method resolution determined at runtime using the object’s actual class.

Question 31

Which methods use static binding?

Answer 31

Static, private, and final methods.

Question 32

Which methods use dynamic binding?

Answer 32

Overridden instance methods.

Question 33

Why is static binding faster?

Answer 33

Because the method call is resolved once at compile time.

Question 34

Why is dynamic binding more flexible?

Answer 34

Because it allows behavior to change depending on the runtime object type.

Question 35

Does method overloading use static or dynamic binding?

Answer 35

Static binding.

Question 36

Does method overriding use static or dynamic binding?

Answer 36

Dynamic binding.

Question 37

What determines dynamic binding execution?

Answer 37

The actual object type at runtime.

Question 38

What determines static binding execution?

Answer 38

The reference type at compile time.

Question 39

Example of dynamic binding?

Answer 39

Animal a = new Dog(); a.sound(); calls Dog’s method.

Question 40

Example of static binding?

Answer 40

Math.max(1,2) is resolved at compile time.

Question 41

Can static methods be dynamically bound?

Answer 41

No. Static methods use compile-time binding.

Question 42

Can constructors use dynamic binding?

Answer 42

No. Constructors are statically bound.

Question 43

Why is dynamic binding essential for polymorphism?

Answer 43

It allows different implementations to execute depending on object type.

Question 44

Key rule to remember?

Answer 44

Compile-time resolution = static binding; runtime resolution = dynamic binding.