Polymorphism in Java with Examples in 2024- Great Learning

What’s Polymorphism in Java?

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

So, languages that don’t assist polymorphism usually are 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 lessons are associated.

Inheritance is a strong characteristic 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 various 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 types. So, polymorphism means innumerable types. Polymorphism, subsequently, is without doubt 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 numerous conditions.

The human physique has totally different organs. Each organ has a special operate to carry out; the center is chargeable for blood movement, the lungs for respiratory, the mind for cognitive exercise, and the kidneys for excretion. So we now have a typical technique operate 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 many others. Every subclass has its means of calculating space. Utilizing Inheritance and Polymorphism means, the subclasses can use the “space()” technique to search out the world’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 Principal {
  public static void most important(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 world of the Triangle is ½ * base * peak
The formulation 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 Principal {
    public static void most important(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 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 most important technique, we create two situations of the Form class, s1 and s2, which are literally situations of the Circle and Sq. subclasses. After we name the draw() technique on these objects, the proper implementation is known as primarily based on the precise kind of the item, 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 called runtime polymorphism or dynamic polymorphism, As a result of at runtime the JVM determines the precise kind of the item and calls the corresponding technique.

Additionally Learn: OOPs ideas in Java

Forms of Polymorphism

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

  1. Technique Overloading
  2. Technique Overriding

What’s Technique Overloading in Java?

Technique overloading is the method that may create a number of strategies of the identical title in the identical class, and all of the strategies work in numerous methods. Technique overloading happens when there may be multiple technique of the identical title within the class.

Instance of Technique 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 Principal {
  public static void most important(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 Technique Overriding in Java?

Technique overriding is the method when the subclass or a toddler class has the identical technique as declared within the dad or mum class.

Instance of Technique Overriding in Java

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

Output:

Automobile is working safely

Additionally, Polymorphism in Java may be labeled 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 Technique Overloading. This sort of polymorphism can be achieved by Operator Overloading. Nevertheless, Java doesn’t assist Operator Overloading.

Technique Overloading is when a category has a number of strategies with the identical title, however the quantity, sorts, and order of parameters and the return kind of the strategies are totally different. Java permits the person freedom to make use of the identical title for numerous capabilities so long as it may well distinguish between them by the sort and variety of parameters. Try among the vital questions on run time polymorphism in java interview questions.

Instance of Compile-Time Polymorphism in Java

We’ll do addition in Java and perceive the idea of compile time polymorphism utilizing subtract() 

package deal 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 most important(String[] args) 
{ 
Addition obj = new Addition(); 
obj.sum ( 30,90); 
obj.sum(45, 80, 22); 
} 
}

The output of this system might be: 

Sum of two numbers: 120 

Sum of three numbers: 147 

On this program, the sum() technique 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 numerous operations through the use of a number of strategies having the identical title.

What’s Runtime Polymorphism in Java?

Runtime polymorphism in Java can also be popularly referred to as Dynamic Binding or Dynamic Technique Dispatch. On this course of, the decision to an overridden technique is resolved dynamically at runtime somewhat than at compile-time. You may obtain Runtime polymorphism through Technique Overriding.

Technique Overriding is finished when a toddler or a subclass has a technique with the identical title, parameters, and return kind because the dad or mum or the superclass; then that operate overrides the operate within the superclass. In easier phrases, if the subclass gives its definition to a technique 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 by capabilities and never knowledge members. 

Overriding is finished through the use of a reference variable of the superclass. The strategy to be referred to as is decided primarily based on the item which is being referred to by the reference variable. That is also referred to as Upcasting.

Upcasting takes place when the Father or mother 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’ll name the eat() technique by the reference variable of Father or mother 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 most important{
  public static void most important(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’ll name the situation() and famousfor() technique by the Father or mother 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 most important{
  public static void most important(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’ll create two lessons 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 most important(String args[]) 
{ 
Automobile c = new innova(); 
c.run(); 
} 
} 

The output of the next program might be; 

Operating quick at 120 km. 

One other instance for run-time polymorphism in Java

Now, allow us to examine if we will obtain runtime polymorphism through knowledge members. 

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

The output of the next program might be : 

125 

This clearly implies we will’t obtain Runtime polymorphism through knowledge members. In brief, 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 most important(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 might 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 Principal 
{ 
public static void most important(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 might 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 implies that a subtype can function one other kind’s subtype, sounds a bit sophisticated? 

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() technique. By overriding draw() with different subclasses comparable to circle, sq., rectangle, trapezium, and many others we’ll introduce an array of kind ‘form’ whose components retailer references will check with ‘form’ subclass references. Subsequent time, we’ll name draw(), all shapes situations draw () technique might 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. In brief, a compiler mustn’t carry out any argument checks, kind checks, technique calls, and many others, and depart every part on the runtime. 

What’s Polymorphism in Programming?

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

What’s Polymorphism Variables?

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

Why use Polymorphism in Java?

Polymorphism in Java makes it potential to jot down a technique that may appropriately course of plenty of several types of functionalities which have the identical title. We are able to additionally acquire consistency in our code through the use of polymorphism.

Benefits of Polymorphism in Java

  1. It gives reusability to the code. The lessons which can 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 knowledge 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 another 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 Technique Overloading and Technique Overriding. They embody:

  • Coercion
  • Inner Operator Overloading
  • Polymorphic Variables or Parameters

1. Coercion

Coercion offers with implicitly changing one kind of object into a brand new object of a special form. Additionally, that is achieved routinely to stop kind errors within the code. 

Programming languages comparable to C, java, and many others assist the conversion of worth from one knowledge kind to a different knowledge kind. Information kind conversions are of two sorts, i.e., implicit and express. 

Implicit kind conversion is routinely achieved in this system and the sort 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 kind error.

Instance:

class coercion {
  public static void most important(String[] args) {
    Double space = 3.14*5*7;
System.out.println(space);
String s = "pleased";
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 assist user-defined operator overloading like C++, the place the person can outline how an operator works for various operands, there are few situations the place Java internally overloads operators.

Operator overloading is the idea of utilizing the operator as per your alternative. Subsequently, an operator image or technique title can be utilized as a ‘user-defined’ kind as per the necessities. 

For instance, ‘+’ can be utilized to carry out the addition of numbers (identical knowledge kind) 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 most important(String[] args) {
    
String s = "pleased";
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 resolve how the operator will interpret.

 3. Polymorphic Variables or Parameters

In Java, the item or occasion variables characterize the polymorphic variables. It is because any object variables of a category can have an IS-A relationship with their very own lessons and subclasses.

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

Parametric polymorphism specifies that whereas class declaration, a subject title can affiliate with differing kinds, and a technique title 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 Principal{
public static void most important(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 is because the superclass’s identical object refers back to the dad or mum class (Form) and the kid class (Triangle). 

Issues with Polymorphism 

With plenty of benefits, there are additionally just a few disadvantages of polymorphism.

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

Kind Identification Throughout Downcasting 

Downcasting is termed as casting to a toddler kind or casting a typical kind to a person kind.

So, we use downcasting at any time when 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 suggests we’re changing widespread kind to particular person kind. 

Vegetable vegetable = new Tomato(); 

Tomato castedTomato = (Tomato) vegetable; 

Right here we’re casting widespread kind to a person kind, superclass to subclass which isn’t potential instantly in java.

We explicitly inform the compiler what the runtime kind of the item is.

Fragile base class downside 

Fragile base class downside is nothing however a basic architectural downside. 

Generally the improper design of a dad or mum 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 downside is termed as a fragile base class downside in object-oriented programming programs and language. 

Mainly, the rationale for the delicate base downside is that the developer of the bottom class has no concept of the subclass design. There is no such thing as a resolution but for this downside. 

Conclusion

We hope you will need to 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, try the programs on Nice Studying Academy and PG Applications in Software program Engineering.  

Additionally, if you’re making ready for Interviews, try these Interview Questions for Java to ace it like a professional.

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

Continuously Requested Questions

What’s polymorphism with instance?

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

What are the 4 kinds of polymorphism?

The 4 kinds 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 through which a particualr factor happens in numerous types. In laptop science, polymorphism describes an idea that permits us to entry several types of objects by the identical interface.

What’s overriding in OOP?

In object-oriented programming, overriding is a characteristic that permits a subclass or baby class to supply a particular implementation of a technique that’s already offered by considered one of its superclasses or dad or mum lessons.

What’s overriding vs overloading?

If two or extra strategies in the identical class have the identical title, however have totally different parameters, this is called Overloading. In case of Overriding, a technique signature (title 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 improvement. For these embarking upon this journey with aspirations in the direction of a profession on this subject, it is strongly recommended to discover the next pages with the intention to purchase a complete understanding of the event profession path:

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