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Polymorphism in Java with Examples in 2024- Nice Studying


What’s Polymorphism in Java?

Polymorphism in Java is the duty that performs a single motion in several methods.

So, languages that don’t help polymorphism are usually not ‘Object-Oriented Languages’, however ‘Object-Based mostly Languages’. Ada, as an example, is one such language. Since Java helps polymorphism, it’s an Object-Oriented Language.

Polymorphism happens when there may be inheritance, i.e., many courses are associated.

Inheritance is a robust function in Java. Java Inheritance lets one class purchase the properties and attributes of one other class. Polymorphism in Java permits us to make use of these inherited properties to carry out totally different duties. Thus, permitting us to realize the identical motion in many alternative methods.

What’s Polymorphism?

The derivation of the phrase Polymorphism is from two totally different Greek words- poly and morphs. “Poly” means quite a few, and “Morphs” means kinds. So, polymorphism means innumerable kinds. Polymorphism, due to this fact, is likely one of the most important options of Object-Oriented Programming.

Should Study Core Java Matters

Actual-Life Examples of Polymorphism

A person can have totally different relationships with totally different folks. A girl could be a mom, a daughter, a sister, and a good friend, all on the identical time, i.e. she performs different behaviors in several conditions.

The human physique has totally different organs. Each organ has a distinct perform to carry out; the guts is answerable for blood stream, the lungs for respiration, the mind for cognitive exercise, and the kidneys for excretion. So we now have a typical methodology perform that performs in a different way relying upon the organ of the physique. 

Polymorphism in Java Instance

A superclass named “Shapes” has a technique referred to as “space()”. Subclasses of “Shapes” may be “Triangle”, “circle”, “Rectangle”, and so on. Every subclass has its method of calculating space. Utilizing Inheritance and Polymorphism means, the subclasses can use the “space()” methodology to seek out the world’s system for that form.

class Shapes {
  public void space() {
    System.out.println("The system for space of ");
  }
}
class Triangle extends Shapes {
  public void space() {
    System.out.println("Triangle is ½ * base * peak ");
  }
}
class Circle extends Shapes {
  public void space() {
    System.out.println("Circle is 3.14 * radius * radius ");
  }
}
class Predominant {
  public static void fundamental(String[] args) {
    Shapes myShape = new Shapes();  // Create a Shapes object
    Shapes myTriangle = new Triangle();  // Create a Triangle object
    Shapes myCircle = new Circle();  // Create a Circle object
    myShape.space();
    myTriangle.space();
    myShape.space();
    myCircle.space();
  }
}

Output:

The system for the world of the Triangle is ½ * base * peak
The system for the world of the Circle is 3.14 * radius * radius

class Form {
    public void draw() {
        System.out.println("Drawing a form");
    }
}

class Circle extends Form {
    @Override
    public void draw() {
        System.out.println("Drawing a circle");
    }
}

class Sq. extends Form {
    @Override
    public void draw() {
        System.out.println("Drawing a sq.");
    }
}

class Predominant {
    public static void fundamental(String[] args) {
        Form s1 = new Circle();
        Form s2 = new Sq.();

        s1.draw(); // Output: "Drawing a circle"
        s2.draw(); // Output: "Drawing a sq."
    }
}

On this instance, we now have a base class Form with a single methodology draw() that prints “Drawing a form” to the console. We then create two subclasses, Circle and Sq., that override the draw() methodology to print “Drawing a circle” and “Drawing a sq.” respectively.

Within the fundamental methodology, we create two cases of the Form class, s1 and s2, which are literally cases of the Circle and Sq. subclasses. After we name the draw() methodology on these objects, the right implementation is named primarily based on the precise sort of the article, that is run-time polymorphism. This system will output: “Drawing a circle” and “Drawing a sq.”

On this instance, the draw() methodology is overridden within the subclasses, and this permits for this system to find out which methodology to make use of at runtime. This is named runtime polymorphism or dynamic polymorphism, As a result of at runtime the JVM determines the precise sort of the article and calls the corresponding methodology.

Additionally Learn: OOPs ideas in Java

Varieties of Polymorphism

You possibly can carry out Polymorphism in Java through two totally different strategies:

  1. Methodology Overloading
  2. Methodology Overriding

What’s Methodology Overloading in Java?

Methodology overloading is the method that may create a number of strategies of the identical identify in the identical class, and all of the strategies work in several methods. Methodology overloading happens when there may be a couple of methodology of the identical identify within the class.

Instance of Methodology Overloading in Java

class Shapes {
  public void space() {
    System.out.println("Discover space ");
  }
public void space(int r) {
    System.out.println("Circle space = "+3.14*r*r);
  }

public void space(double b, double h) {
    System.out.println("Triangle space="+0.5*b*h);
  }
public void space(int l, int b) {
    System.out.println("Rectangle space="+l*b);
  }


}

class Predominant {
  public static void fundamental(String[] args) {
    Shapes myShape = new Shapes();  // Create a Shapes object
    
    myShape.space();
    myShape.space(5);
    myShape.space(6.0,1.2);
    myShape.space(6,2);
    
  }
}

Output:

Discover space
Circle space = 78.5
Triangle space=3.60
Rectangle space=12

What’s Methodology Overriding in Java?

Methodology overriding is the method when the subclass or a baby class has the identical methodology as declared within the father or mother class.

Instance of Methodology Overriding in Java

class Car{  
  //defining a technique  
  void run(){System.out.println("Car is shifting");}  
}  
//Creating a baby class  
class Car2 extends Car{  
  //defining the identical methodology as within the father or mother class  
  void run(){System.out.println("automobile is working safely");}  
  
  public static void fundamental(String args[]){  
  Car2 obj = new Car2();//creating object  
  obj.run();//calling methodology  
  }  
}  

Output:

Automotive is working safely

Additionally, Polymorphism in Java may be categorized into two sorts, i.e:

  1. Static/Compile-Time Polymorphism
  2. Dynamic/Runtime Polymorphism

What’s Compile-Time Polymorphism in Java?

Compile Time Polymorphism In Java is also referred to as Static Polymorphism. Moreover, the decision to the strategy is resolved at compile-time. Compile-Time polymorphism is achieved by way of Methodology Overloading. One of these polymorphism may also be achieved by way of Operator Overloading. Nonetheless, Java doesn’t help Operator Overloading.

Methodology Overloading is when a category has a number of strategies with the identical identify, however the quantity, sorts, and order of parameters and the return sort of the strategies are totally different. Java permits the person freedom to make use of the identical identify for varied features so long as it could distinguish between them by the sort and variety of parameters. Take a look at a number of the vital questions on run time polymorphism in java interview questions.

Instance of Compile-Time Polymorphism in Java

We are going to do addition in Java and perceive the idea of compile time polymorphism utilizing subtract() 

bundle staticPolymorphism; 
public class Addition 
{ 
void sum(int a, int b) 
{ 
int c = a+b; 
System.out.println(“ Addition of two numbers :” +c); } 
void sum(int a, int b, int e) 
{ 
int c = a+b+e; 
System.out.println(“ Addition of three numbers :” +c); } 
public static void fundamental(String[] args) 
{ 
Addition obj = new Addition(); 
obj.sum ( 30,90); 
obj.sum(45, 80, 22); 
} 
}

The output of this system will probably be: 

Sum of two numbers: 120 

Sum of three numbers: 147 

On this program, the sum() methodology overloads with two sorts through totally different parameters. 

That is the essential idea of compile-time polymorphism in java the place we will carry out varied operations through the use of a number of strategies having the identical identify.

What’s Runtime Polymorphism in Java?

Runtime polymorphism in Java can also be popularly generally known as Dynamic Binding or Dynamic Methodology Dispatch. On this course of, the decision to an overridden methodology is resolved dynamically at runtime quite than at compile-time. You possibly can obtain Runtime polymorphism through Methodology Overriding.

Methodology Overriding is completed when a baby or a subclass has a technique with the identical identify, parameters, and return sort because the father or mother or the superclass; then that perform overrides the perform within the superclass. In easier phrases, if the subclass supplies its definition to a technique already current within the superclass; then that perform within the base class is alleged to be overridden.

Additionally, it must be famous that runtime polymorphism can solely be achieved by way of features and never information members. 

Overriding is completed through the use of a reference variable of the superclass. The tactic to be referred to as is set primarily based on the article which is being referred to by the reference variable. That is also referred to as Upcasting.

Upcasting takes place when the Guardian class’s reference variable refers back to the object of the kid class. For instance:

class A{} 
class B extends A{}  
A a=new B(); //upcasting

Examples of Runtime Polymorphism in Java

Instance 1:

On this instance, we’re creating one superclass Animal and three subclasses, Herbivores, Carnivores, and Omnivores. Subclasses prolong the superclass and override its eat() methodology. We are going to name the eat() methodology by the reference variable of Guardian class, i.e. Animal class. Because it refers back to the base class object and the bottom class methodology overrides the superclass methodology; the bottom class methodology is invoked at runtime. As Java Digital Machine or the JVM and never the compiler determines methodology invocation, it’s, due to this fact, runtime polymorphism.

class Animal{  
  void eat(){
System.out.println("Animals Eat");
}  
}  
class herbivores extends Animal{  
  void eat(){
System.out.println("Herbivores Eat Crops");
} 
  }
class omnivores extends Animal{  
  void eat(){
System.out.println("Omnivores Eat Crops and meat");
} 
  }
class carnivores extends Animal{  
  void eat(){
System.out.println("Carnivores Eat meat");
} 
  }
class fundamental{
  public static void fundamental(String args[]){ 
    Animal A = new Animal();
    Animal h = new herbivores(); //upcasting  
	Animal o = new omnivores(); //upcasting  
    Animal c = new carnivores(); //upcasting  
    A.eat();
    h.eat();
    o.eat();  
    c.eat();  
  
  }  
}  

Output:

Animals eat
Herbivores Eat Crops
Omnivores Eat Crops and meat
Carnivores eat meat

Instance 2:

On this instance, we’re creating one superclass Hillstations and three subclasses Manali, Mussoorie, Gulmarg. Subclasses prolong the superclass and override its location() and famousfor() methodology. We are going to name the placement() and famousfor() methodology by the Guardian class’, i.e. Hillstations class. Because it refers back to the base class object and the bottom class methodology overrides the superclass methodology; the bottom class methodology is invoked at runtime. Additionally, as Java Digital Machine or the JVM and never the compiler determines methodology invocation, it’s runtime polymorphism.

class Hillstations{  
  void location(){
System.out.println("Location is:");
}  
void famousfor(){
System.out.println("Well-known for:");
}  

}  
class Manali extends Hillstations {  
  void location(){
System.out.println("Manali is in Himachal Pradesh");
}  
void famousfor(){
System.out.println("It's Well-known for Hadimba Temple and journey sports activities");
}  
  }
class Mussoorie extends Hillstations {  
  void location(){
System.out.println("Mussoorie is in Uttarakhand");
}  
void famousfor(){
System.out.println("It's Well-known for training establishments");
}  
  }
class Gulmarg extends Hillstations {  
  void location(){
System.out.println("Gulmarg is in J&Ok");
}  
void famousfor(){
System.out.println("It's Well-known for snowboarding");
}  
  }
class fundamental{
  public static void fundamental(String args[]){ 
    Hillstations A = new Hillstations();
    Hillstations M = new Manali();

    Hillstations Mu = new Mussoorie();

    Hillstations G = new Gulmarg();

    A.location();
A.famousfor();

M.location();
M.famousfor();

Mu.location();
Mu.famousfor();

G.location();
G.famousfor();
  }  
}  

Output:

Location is:
Well-known for:
Manali is in Himachal Pradesh
It’s Well-known for Hadimba Temple and journey sports activities
Mussoorie is in Uttarakhand
It’s Well-known for training establishments
Gulmarg is in J&Ok
It’s Well-known for snowboarding

Instance of run-time polymorphism in java

We are going to create two courses Automotive and Innova, Innova class will prolong the automobile class and can override its run() methodology.

class Automotive 
{ 
void run() 
{ 
System.out.println(“ working”); 
} 
}
class innova extends Automotive 
{ 
void run(); 
{ 
System.out.println(“ working quick at 120km”); 
} 
public static void fundamental(String args[]) 
{ 
Automotive c = new innova(); 
c.run(); 
} 
} 

The output of the next program will probably be; 

Operating quick at 120 km. 

One other instance for run-time polymorphism in Java

Now, allow us to test if we will obtain runtime polymorphism through information members. 

class automobile 
{ 
int speedlimit = 125; 
} 
class innova extends automobile 
{ 
int speedlimit = 135; 
public static void fundamental(String args[]) 
{ 
automobile obj = new innova(); 
System.out.println(obj.speedlimit);
}

The output of the next program will probably be : 

125 

This clearly implies we will’t obtain Runtime polymorphism through information members. Briefly, a technique is overridden, not the information members.

Runtime polymorphism with multilevel inheritance

class grandfather 
{ 
void swim() 
{ 
System.out.println(“ Swimming”); 
} 
} 
class father extends grandfather 
{ 
void swim() 
{ 
System.out.println(“ Swimming in river”); 
} 
} 
class son extends father 
{ 
void swim() 
{ 
System.out.println(“ Swimming in pool”);
} 
public static void fundamental(String args[]) 
{ 
grandfather f1,f2,f3; 
f1 =new grandfather(); 
f2 = new father(); 
f3 = new son(); 
f1.swim(); 
f2.swim(); 
f3.swim(): 
} 
} 

The output of the next program will probably be: 

Swimming, Swimming in river, Swimming in pool

One other runtime polymorphism with multilevel inheritance instance

class soundAnimal 
{ 
public void Sound() 
{ 
System.out.println("Completely different sounds of animal"); }
} 
class buffalo extends soundAnimal 
{ 
public void Sound() 
{ 
System.out.println("The buffalo sound- gho,gho"); } 
} 
class snake extends soundAnimal 
{ 
public void Sound() 
{ 
System.out.println("The snake sound- his,his"); } 
} 
class tiger extends soundAnimal
{ 
public void Sound() 
{ 
System.out.println("The tiger sounds- roooo, rooo"); } 
} 
public class Animal Predominant 
{ 
public static void fundamental(String[] args) 
{ 
soundAnimal Animal = new soundAnimal(); soundAnimal buffalo = new buffalo(); 
soundAnimal snake = new snake(); 
soundAnimal tiger = new tiger(); 
Animal.Sound(); 
buffalo.Sound();
snake.Sound(); 
tiger.Sound(); 
} 
} 

The output of the next program will probably be; 

The buffalo sound- gho,gho 

The snake sound- his,his 

The tiger sound- roooo,roooo 

We hope you bought an concept about runtime and compile-time polymorphism.

Polymorphic Subtypes

Subtype mainly signifies that a subtype can function one other sort’s subtype, sounds a bit difficult? 

Let’s perceive this with the assistance of an instance:

Assuming we now have to attract some arbitrary shapes, we will introduce a category named ‘form’ with a draw() methodology. By overriding draw() with different subclasses reminiscent of circle, sq., rectangle, trapezium, and so on we’ll introduce an array of sort ‘form’ whose parts retailer references will discuss with ‘form’ subclass references. Subsequent time, we’ll name draw(), all shapes cases draw () methodology will probably be referred to as.

This Subtype polymorphism usually depends on upcasting and late binding. A casting the place you forged up the inheritance hierarchy from subtype to a supertype is termed upcasting.

To name non-final occasion strategies we use late binding. Briefly, a compiler shouldn’t carry out any argument checks, sort checks, methodology calls, and so on, and go away every little thing on the runtime. 

What’s Polymorphism in Programming?

Polymorphism in programming is outlined utilization of a single image to signify a number of differing kinds.

What’s Polymorphism Variables?

A polymorphic variable is outlined as a variable that may maintain values of various sorts through the course of execution.

Why use Polymorphism in Java?

Polymorphism in Java makes it attainable to put in writing a technique that may appropriately course of a number of several types of functionalities which have the identical identify. We are able to additionally achieve consistency in our code through the use of polymorphism.

Benefits of Polymorphism in Java

  1. It supplies reusability to the code. The courses which might be written, examined and applied may be reused a number of occasions. Moreover, it saves a number of time for the coder. Additionally, the one can change the code with out affecting the unique code.
  2. A single variable can be utilized to retailer a number of information values. The worth of a variable you inherit from the superclass into the subclass may be modified with out altering that variable’s worth within the superclass; or every other subclasses.
  3. With lesser strains of code, it turns into simpler for the programmer to debug the code.

Traits of Polymorphism

Polymorphism has many different traits apart from Methodology Overloading and Methodology Overriding. They embrace:

  • Coercion
  • Inner Operator Overloading
  • Polymorphic Variables or Parameters

1. Coercion

Coercion offers with implicitly changing one sort of object into a brand new object of a distinct variety. Additionally, that is performed robotically to forestall sort errors within the code. 

Programming languages reminiscent of C, java, and so on help the conversion of worth from one information sort to a different information sort. Information sort conversions are of two sorts, i.e., implicit and specific. 

Implicit sort conversion is robotically performed in this system and this kind of conversion can also be termed coercion. 

For instance, if an operand is an integer and one other one is in float, the compiler implicitly converts the integer into float worth to keep away from sort error.

Instance:

class coercion {

  public static void fundamental(String[] args) {
    Double space = 3.14*5*7;
System.out.println(space);
String s = "glad";
int x=5;
String phrase = s+x;
System.out.println(phrase);

  }
}

Output:

109.9
happy5

2. Inner Operator Overloading

In Operator Overloading, an operator or image behaves in additional methods than one relying upon the enter context or the kind of operands. It’s a attribute of static polymorphism. Though Java doesn’t help user-defined operator overloading like C++, the place the person can outline how an operator works for various operands, there are few cases the place Java internally overloads operators.

Operator overloading is the idea of utilizing the operator as per your selection. Due to this fact, an operator image or methodology identify can be utilized as a ‘user-defined’ sort as per the necessities. 

For instance, ‘+’ can be utilized to carry out the addition of numbers (identical information sort) or for concatenation of two or extra strings.

Within the case of +, can be utilized for addition and likewise for concatenation.

For instance:

class coercion {

  public static void fundamental(String[] args) {
    
String s = "glad";
String s1 = "world";
int x=5;
int y=10;

System.out.println(s+s1);
System.out.println(x+y);

  }
}

Output :

Equally, operators like! &, and | are additionally within the overload place for logical and bitwise operations. In each of those instances, the kind of argument will resolve how the operator will interpret.

 3. Polymorphic Variables or Parameters

In Java, the article or occasion variables signify the polymorphic variables. It’s because any object variables of a category can have an IS-A relationship with their very own courses and subclasses.

The Polymorphic Variable is a variable that may maintain values of various sorts through the time of execution.

Parametric polymorphism specifies that whereas class declaration, a discipline identify can affiliate with differing kinds, and a technique identify can affiliate with totally different parameters and return sorts.

For instance:

class Form
{
public void show()
{
System.out.println("A Form.");
}
}
class Triangle extends Form
{
public void show()
{
System.out.println("I'm a triangle.");
}
}
class Predominant{
public static void fundamental(String[] args)
{
Form obj;
obj = new Form();
obj.show();
obj = new Triangle();
obj.show();
}
}

Output:

A Form.
I’m a triangle.

Right here, the obj object is a polymorphic variable. It’s because the superclass’s identical object refers back to the father or mother class (Form) and the kid class (Triangle). 

Issues with Polymorphism 

With a number of benefits, there are additionally a number of disadvantages of polymorphism.

  • Polymorphism is sort of difficult whereas implementation.
  • It tends to cut back the readability of the code.
  • It raises some critical efficiency points in real-time as effectively.

Kind Identification Throughout Downcasting 

Downcasting is termed as casting to a baby sort or casting a typical sort to a person sort.

So, we use downcasting at any time when we have to entry or perceive the behaviour of the subtypes. 

Instance, 

It is a hierarchical instance 

Meals> Vegetable> Ladyfinger, Tomato 

Right here, tomato and ladyfinger are two subclasses. 

In downcasting, we slim the kind of objects, which suggests we’re changing widespread sort to particular person sort. 

Vegetable vegetable = new Tomato(); 

Tomato castedTomato = (Tomato) vegetable; 

Right here we’re casting widespread sort to a person sort, superclass to subclass which isn’t attainable immediately in java.

We explicitly inform the compiler what the runtime sort of the article is.

Fragile base class drawback 

Fragile base class drawback is nothing however a elementary architectural drawback. 

Generally the improper design of a father or mother class can lead a subclass of a superclass to make use of superclass in some unpredicted methods. 

The fragility of inheritance will result in damaged codes even when all the standards is met. 

This architectural drawback is termed as a fragile base class drawback in object-oriented programming programs and language. 

Principally, the explanation for the delicate base drawback is that the developer of the bottom class has no concept of the subclass design. There is no such thing as a answer but for this drawback. 

Conclusion

We hope you should have gotten a primary concept of polymorphism in Java and the way we use it in addition to issues associated to them. 

Therefore, this brings us to the tip of the weblog on Polymorphism in Java. Moreover, to be taught extra about programming and different associated ideas, take a look at the programs on Nice Studying Academy and PG Applications in Software program Engineering.  

Additionally, if you’re getting ready for Interviews, take a look at these Interview Questions for Java to ace it like a professional.

So, don’t cease your journey of studying. Additionally, don’t neglect to upskill and reskill your self. Maintain exploring and continue to learn.

Incessantly Requested Questions

What’s polymorphism with instance?

One of many OOPs options that permits us to hold out a single motion in varied methods is named polymorphism in Java. For instance, we now have a category Animal with a technique sound(). It is a generic class and so we can’t give it an implementation reminiscent of: Meow, Oink, Roar, and so on. 

What are the 4 varieties of polymorphism?

The 4 varieties of polymorphism are:
– Runtime or Subtype polymorphism
– Overloading or Parametric polymorphism
– Compile-time or Advert hoc polymorphism
– Casting or Coercion polymorphism

What’s polymorphism in OOPs?

One of many core ideas of OOP or object-oriented programming, polymorphism describes conditions wherein a particualr factor happens in several kinds. In laptop science, polymorphism describes an idea that permits us to entry several types of objects by way of the identical interface.

What’s overriding in OOP?

In object-oriented programming, overriding is a function that permits a subclass or youngster class to offer a particular implementation of a technique that’s already supplied by considered one of its superclasses or father or mother courses.

What’s overriding vs overloading?

If two or extra strategies in the identical class have the identical identify, however have totally different parameters, this is named Overloading. In case of Overriding, a technique signature (identify and parameters) are present in the identical superclass and the kid class.

Participating within the research of Java programming suggests a eager curiosity within the realm of software program growth. For these embarking upon this journey with aspirations in direction of a profession on this discipline, it’s endorsed to discover the next pages in an effort to purchase a complete understanding of the event profession path:

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