Chapter 8 - Polymorphism

Question 1

Definiton of polymorphism

Answer 1

Polymorphism in Java is like having a universal remote control. Imagine you have different types of electronic devices (TV, DVD player, sound system) with their own unique functions. The universal remote, in this case, is like a common interface or superclass.

Polymorphism is a concept by which we can perform a single task in different ways. That is, when a single entity (object) behaves differently in different cases, it is called polymorphism.

allows objects of different classes to be treated as objects of a common superclass. It enables you to write flexible and extensible code by providing a way to work with objects of multiple types without needing to know their specific implementations.

With polymorphism, you can use this universal remote to control any device, even though each device has its specific features. You don’t need to know the inner workings of each device; you can simply press the buttons on the universal remote, and it sends the right commands to the device you’re currently using.

In Java, this means you can write code that works with objects from various classes as long as they share a common superclass or interface. You can treat these objects uniformly, even though they may have different implementations behind the scenes. This flexibility simplifies your code and makes it more versatile.

Question 2

Compile time polimrphism

Answer 2

Method Overloading:

Method overloading is a form of compile-time (static) polymorphism.
It allows you to define multiple methods in the same class with the same name but different parameters (different method signatures).
The Java compiler determines which method to call based on the number, type, and order of arguments provided during the method invocation.

Question 3

Runtime polimrphism

Answer 3

Method Overriding:

Method overriding is a form of runtime (dynamic) polymorphism.
It occurs when a subclass provides a specific implementation of a method that is already defined in its superclass.
The overridden method in the subclass should have the same method signature (method name, return type, and parameter list) as the method in the superclass.
When you call an overridden method on an object of the subclass, the subclass’s implementation is executed.

Question 4

Polymorphic Reference

Answer 4

Polymorphic reference is a concept in Java that allows you to create a reference variable of a parent class type and then assign it an object of a child class.

Animal myAnimal;
myAnimal = new Dog();

    myAnimal.makeSound();

Question 5

Late Binding (Dynamic Binding)

Answer 5

In polymorphism, the method to be executed is determined at runtime (late binding), not at compile time.
This allows for flexibility in choosing the appropriate method implementation based on the actual object type.

Question 6

How is Inheritance useful to achieve Polymorphism in Java?

Answer 6

Inheritance represents the parent-child relationship between two classes and polymorphism take the advantage of that relationship to add dynamic behavior in the code (or to make the program more dynamic).

Question 7

What are the differences between Polymorphism and Inheritance in Java?

Answer 7

Inheritance helps in code reusability in child class by inheriting behavior from parent class. On the other hand, polymorphism enables child class to redefine already defined behavior inside parent class.

Question 8

What is Binding in Java?

Answer 8

The connecting (linking) between a method call and method definition is called binding in java.

Question 9

What are the types of binding in Java?

Answer 9

There are two types of binding in java. They are as follows:

a. Static Binding (also known as Early Binding).
b. Dynamic Binding (also known as Late Binding).

Question 10

What is Static binding in Java?

Answer 10

The binding that happens during compilation is called static binding in java. This binding is resolved at the compiled time by the compiler.

Question 11

How Java compiler performs static binding?

Answer 11

Java compiler just checks which method is going to be called through reference variable and method definition exists or not.

Question 12

Why static binding is also called early binding in Java?

Answer 12

Static binding is also called early binding because it takes place before the program actually runs.

Question 13

Give an example of static binding.

Answer 13

An example of static binding is method overloading.

Question 14

What is Dynamic binding in Java?

Answer 14

The binding which occurs during runtime is called dynamic binding in java. This binding is resolved based on the type of object at runtime.

Question 15

How JVM performs dynamic binding in Java?

Answer 15

In the dynamic binding, the actual object is used for binding at runtime. JVM resolved the method calls based on the type of object at runtime. The type of object cannot be determined by the compiler.

Question 16

Why Dynamic binding is also called late binding in java?

Answer 16

Dynamic binding is also called late binding or runtime binding because binding occurs during runtime.

Question 17

Give an example of dynamic binding in Java.

Answer 17

An example of dynamic binding is method overriding.

Question 18

Why binding of private, static, and final methods are always static binding in Java?

Answer 18

Static binding is better performance-wise because java compiler knows that all such methods cannot be overridden and will always be accessed by object reference variable.

Hence, the compiler doesn’t have any difficulty in binding between a method call and method definition. That’s why binding for such methods is always static.