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 numerous methods.

So, languages that don’t help polymorphism aren’t ‘Object-Oriented Languages’, however ‘Object-Based mostly Languages’. Ada, as an illustration, 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, subsequently, is among the most vital options of Object-Oriented Programming.

Actual-Life Examples of Polymorphism

A person can have totally different relationships with totally different individuals. A girl is usually a mom, a daughter, a sister, and a good friend, all on the similar time, i.e. she performs different behaviors in numerous conditions.

The human physique has totally different organs. Each organ has a unique operate to carry out; the center is answerable for blood circulation, the lungs for respiration, the mind for cognitive exercise, and the kidneys for excretion. So now we have a typical technique operate that performs in another way relying upon the organ of the physique. 

Polymorphism in Java Instance

A superclass named “Shapes” has a way known as “space()”. Subclasses of “Shapes” will be “Triangle”, “circle”, “Rectangle”, and so forth. Every subclass has its manner of calculating space. Utilizing Inheritance and Polymorphism means, the subclasses can use the “space()” technique to seek out the realm’s formulation for that form.

class Shapes {
  public void space() {
    System.out.println("The formulation 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 essential(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 formulation for the realm of the Triangle is ½ * base * peak
The formulation for the realm 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 essential(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, now we have a base class Form with a single technique draw() that prints “Drawing a form” to the console. We then create two subclasses, Circle and Sq., that override the draw() technique to print “Drawing a circle” and “Drawing a sq.” respectively.

Within the essential technique, 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() technique on these objects, the right implementation known as based mostly on the precise sort of the thing, that is run-time polymorphism. This system will output: “Drawing a circle” and “Drawing a sq.”

On this instance, the draw() technique is overridden within the subclasses, and this permits for this system to find out which technique 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 thing and calls the corresponding technique.

Additionally Learn: OOPs ideas in Java

Kinds of Polymorphism

You’ll be able to carry out Polymorphism in Java by way of 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 numerous methods. Methodology overloading happens when there may be multiple technique 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 essential(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 toddler class has the identical technique as declared within the mum or dad class.

Instance of Methodology Overriding in Java

class Car{  
  //defining a way  
  void run(){System.out.println("Car is transferring");}  
}  
//Creating a toddler class  
class Car2 extends Car{  
  //defining the identical technique as within the mum or dad class  
  void run(){System.out.println("automotive is working safely");}  
  
  public static void essential(String args[]){  
  Car2 obj = new Car2();//creating object  
  obj.run();//calling technique  
  }  
}  

Output:

Automobile is working safely

Additionally, Polymorphism in Java will be labeled into two varieties, i.e:

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

What’s Compile-Time Polymorphism in Java?

Compile Time Polymorphism In Java is often known as Static Polymorphism. Moreover, the decision to the strategy is resolved at compile-time. Compile-Time polymorphism is achieved via Methodology Overloading. One of these polymorphism can be achieved via Operator Overloading. Nevertheless, Java doesn’t help Operator Overloading.

Methodology Overloading is when a category has a number of strategies with the identical identify, however the quantity, varieties, 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 numerous capabilities so long as it could actually distinguish between them by the kind and variety of parameters. Take a look at a number of the necessary 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 essential(String[] args) 
{ 
Addition obj = new Addition(); 
obj.sum ( 30,90); 
obj.sum(45, 80, 22); 
} 
}

The output of this system can be: 

Sum of two numbers: 120 

Sum of three numbers: 147 

On this program, the sum() technique overloads with two varieties by way of totally different parameters. 

That is the fundamental idea of compile-time polymorphism in java the place we are able to carry out numerous operations by utilizing a number of strategies having the identical identify.

What’s Runtime Polymorphism in Java?

Runtime polymorphism in Java can also be popularly often called Dynamic Binding or Dynamic Methodology Dispatch. On this course of, the decision to an overridden technique is resolved dynamically at runtime slightly than at compile-time. You’ll be able to obtain Runtime polymorphism by way of Methodology Overriding.

Methodology Overriding is completed when a toddler or a subclass has a way with the identical identify, parameters, and return sort because the mum or dad or the superclass; then that operate overrides the operate within the superclass. In easier phrases, if the subclass supplies its definition to a way already current within the superclass; then that operate within the base class is claimed to be overridden.

Additionally, it ought to be famous that runtime polymorphism can solely be achieved via capabilities and never knowledge members. 

Overriding is completed by utilizing a reference variable of the superclass. The tactic to be known as is set based mostly on the thing which is being referred to by the reference variable. That is often known as Upcasting.

Upcasting takes place when the Mother or father 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() technique. We are going to name the eat() technique by the reference variable of Mother or father class, i.e. Animal class. Because it refers back to the base class object and the bottom class technique overrides the superclass technique; the bottom class technique is invoked at runtime. As Java Digital Machine or the JVM and never the compiler determines technique invocation, it’s, subsequently, runtime polymorphism.

class Animal{  
  void eat(){
System.out.println("Animals Eat");
}  
}  
class herbivores extends Animal{  
  void eat(){
System.out.println("Herbivores Eat Vegetation");
} 
  }
class omnivores extends Animal{  
  void eat(){
System.out.println("Omnivores Eat Vegetation and meat");
} 
  }
class carnivores extends Animal{  
  void eat(){
System.out.println("Carnivores Eat meat");
} 
  }
class essential{
  public static void essential(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 Vegetation
Omnivores Eat Vegetation 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() technique. We are going to name the situation() and famousfor() technique by the Mother or father class’, i.e. Hillstations class. Because it refers back to the base class object and the bottom class technique overrides the superclass technique; the bottom class technique is invoked at runtime. Additionally, as Java Digital Machine or the JVM and never the compiler determines technique 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 schooling establishments");
}  
  }
class Gulmarg extends Hillstations {  
  void location(){
System.out.println("Gulmarg is in J&Okay");
}  
void famousfor(){
System.out.println("It's Well-known for snowboarding");
}  
  }
class essential{
  public static void essential(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 schooling establishments
Gulmarg is in J&Okay
It’s Well-known for snowboarding

Instance of run-time polymorphism in java

We are going to create two courses Automobile and Innova, Innova class will prolong the automotive class and can override its run() technique.

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

The output of the next program can be; 

Working quick at 120 km. 

One other instance for run-time polymorphism in Java

Now, allow us to test if we are able to obtain runtime polymorphism by way of knowledge members. 

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

The output of the next program can be : 

125 

This clearly implies we are able to’t obtain Runtime polymorphism by way of knowledge members. In brief, a way is overridden, not the info 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 essential(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 can be: 

Swimming, Swimming in river, Swimming in pool

One other runtime polymorphism with multilevel inheritance instance

class soundAnimal 
{ 
public void Sound() 
{ 
System.out.println("Totally 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 essential(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 can be; 

The buffalo sound- gho,gho 

The snake sound- his,his 

The tiger sound- roooo,roooo 

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

Polymorphic Subtypes

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

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

Assuming now we have to attract some arbitrary shapes, we are able to introduce a category named ‘form’ with a draw() technique. By overriding draw() with different subclasses comparable to circle, sq., rectangle, trapezium, and so forth we’ll introduce an array of sort ‘form’ whose parts retailer references will seek advice from ‘form’ subclass references. Subsequent time, we’ll name draw(), all shapes cases draw () technique can be known 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. In brief, a compiler mustn’t carry out any argument checks, sort checks, technique calls, and so forth, and depart every part 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 varieties throughout the course of execution.

Why use Polymorphism in Java?

Polymorphism in Java makes it doable to jot down a way that may appropriately course of numerous various kinds of functionalities which have the identical identify. We are able to additionally achieve consistency in our code by utilizing polymorphism.

Benefits of Polymorphism in Java

1. It supplies reusability to the code. The courses which are written, examined and carried out will be reused a number of instances. 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 knowledge values. The worth of a variable you inherit from the superclass into the subclass will be modified with out altering that variable’s worth within the superclass; or every other subclasses.
3. With lesser traces of code, it turns into simpler for the programmer to debug the code.

Traits of Polymorphism

Polymorphism has many different traits aside from Methodology Overloading and Methodology Overriding. They embody:

• Coercion
• Inside Operator Overloading
• Polymorphic Variables or Parameters

1. Coercion

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

Programming languages comparable to C, java, and so forth help the conversion of worth from one knowledge sort to a different knowledge sort. Information sort conversions are of two varieties, i.e., implicit and express. 

Implicit sort conversion is robotically finished in this system and any such 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 essential(String[] args) {
    Double space = 3.14*5*7;
System.out.println(space);
String s = "blissful";
int x=5;
String phrase = s+x;
System.out.println(phrase);

  }
}

Output:

109.9
happy5

2. Inside 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 technique 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 (similar knowledge sort) or for concatenation of two or extra strings.

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

For instance:

class coercion {

  public static void essential(String[] args) {
    
String s = "blissful";
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 circumstances, the kind of argument will determine how the operator will interpret.

 3. Polymorphic Variables or Parameters

In Java, the thing 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 varieties throughout the time of execution.

Parametric polymorphism specifies that whereas class declaration, a subject identify can affiliate with differing kinds, and a way identify can affiliate with totally different parameters and return varieties.

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 essential(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 similar object refers back to the mum or dad class (Form) and the kid class (Triangle). 

Issues with Polymorphism 

With numerous benefits, there are additionally a couple of disadvantages of polymorphism.

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

Sort Identification Throughout Downcasting 

Downcasting is termed as casting to a toddler sort or casting a standard sort to a person sort.

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

Instance, 

This can be a hierarchical instance 

Meals> Vegetable> Ladyfinger, Tomato 

Right here, tomato and ladyfinger are two subclasses. 

In downcasting, we slender the kind of objects, which implies we’re changing frequent sort to particular person sort. 

Vegetable vegetable = new Tomato(); 

Tomato castedTomato = (Tomato) vegetable; 

Right here we’re casting frequent sort to a person sort, superclass to subclass which isn’t doable straight in java.

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

Fragile base class drawback 

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

Generally the improper design of a mum or dad 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 rationale for the delicate base drawback is that the developer of the bottom class has no thought of the subclass design. There isn’t a answer but for this drawback. 

Conclusion

We hope you need to have gotten a fundamental thought of polymorphism in Java and the way we use it in addition to issues associated to them. 

Therefore, this brings us to the top 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 Packages 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 learning.

Incessantly Requested Questions

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