What’s Polymorphism in Java?

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

So, languages that don’t assist polymorphism should not ‘Object-Oriented Languages’, however ‘Object-Primarily based Languages’. Ada, as an illustration, is one such language. Since Java helps polymorphism, it’s an Object-Oriented Language.

Polymorphism happens when there’s inheritance, i.e., many lessons are associated.

Inheritance is a robust 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 attain 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 varieties. So, polymorphism means innumerable varieties. Polymorphism, due to this fact, is without doubt one of the most important options of Object-Oriented Programming.

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 buddy, all on the similar time, i.e. she performs different behaviors in several conditions.

The human physique has totally different organs. Each organ has a unique perform to carry out; the guts is chargeable for blood circulation, the lungs for respiratory, the mind for cognitive exercise, and the kidneys for excretion. So we’ve got a typical technique perform that performs in another 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 forth. 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 method for that form.

class Shapes {
  public void space() {
    System.out.println("The method 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 Primary {
  public static void primary(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 method for the world of the Triangle is ½ * base * peak
The method 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 Primary {
    public static void primary(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’ve got 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 primary 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 proper implementation is named based mostly 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() 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 article and calls the corresponding technique.

Additionally Learn: OOPs ideas in Java

Varieties of Polymorphism

You’ll be able to 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 title in the identical class, and all of the strategies work in several methods. Methodology overloading happens when there’s multiple technique of the identical title 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 Primary {
  public static void primary(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 technique as declared within the mother or father class.

Instance of Methodology Overriding in Java

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

Output:

Automotive is working safely

Additionally, Polymorphism in Java may be categorised 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 tactic is resolved at compile-time. Compile-Time polymorphism is achieved by way of Methodology Overloading. This kind of polymorphism may also be achieved by way of Operator Overloading. Nonetheless, Java doesn’t assist Operator Overloading.

Methodology Overloading is when a category has a number of strategies with the identical title, however the quantity, varieties, and order of parameters and the return sort of the strategies are totally different. Java permits the consumer freedom to make use of the identical title for varied features so long as it will probably distinguish between them by the sort and variety of parameters. Try a few 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 primary(String[] args) 
{ 
Addition obj = new Addition(); 
obj.sum ( 30,90); 
obj.sum(45, 80, 22); 
} 
}

The output of this system will likely be: 

Sum of two numbers: 120 

Sum of three numbers: 147 

On this program, the sum() technique overloads with two varieties 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 title.

What’s Runtime Polymorphism in Java?

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

Methodology Overriding is finished when a baby or a subclass has a technique with the identical title, parameters, and return sort because the mother or father 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 claimed to be overridden.

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

Overriding is finished through the use of a reference variable of the superclass. The strategy to be referred to as is set based mostly on the article which is being referred to by the reference variable. That is often known 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() technique. We are going to name the eat() technique by the reference variable of Guardian 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, 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 primary{
  public static void primary(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() technique. We are going to name the situation() and famousfor() technique by the Guardian 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 training 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 primary{
  public static void primary(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&Okay
It’s Well-known for snowboarding

Instance of run-time polymorphism in java

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

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

The output of the next program will likely be; 

Working 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 information members. 

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

The output of the next program will likely 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 primary(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 likely 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 Primary 
{ 
public static void primary(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 likely 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 principally 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’ve got to attract some arbitrary shapes, we will introduce a category named ‘form’ with a draw() technique. By overriding draw() with different subclasses reminiscent of circle, sq., rectangle, trapezium, and so forth we’ll introduce an array of sort ‘form’ whose components retailer references will confer with ‘form’ subclass references. Subsequent time, we’ll name draw(), all shapes cases draw () technique will likely be referred to as.

This Subtype polymorphism typically 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, technique calls, and so forth, and go away every thing on the runtime. 

What’s Polymorphism in Programming?

Polymorphism in programming is outlined utilization of a single image to symbolize a number of differing types.

What’s Polymorphism Variables?

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

Why use Polymorphism in Java?

Polymorphism in Java makes it attainable to jot down a technique that may appropriately course of numerous various kinds 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 supplies reusability to the code. The lessons which might be written, examined and carried out may be reused a number of instances. Moreover, it saves a variety 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 another 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
• 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 sort. Additionally, that is performed mechanically to stop sort errors within the code. 

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

Implicit sort conversion is mechanically performed in this system and this kind of conversion can 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 primary(String[] args) {
    Double space = 3.14*5*7;
System.out.println(space);
String s = "completely happy";
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 assist user-defined operator overloading like C++, the place the consumer 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 alternative. Subsequently, an operator image or technique title 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 information 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 primary(String[] args) {
    
String s = "completely happy";
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 article or occasion variables symbolize 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 varieties in the course of the time of execution.

Parametric polymorphism specifies that whereas class declaration, a subject title can affiliate with differing types, and a technique title 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 Primary{
public static void primary(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 similar object refers back to the mother or father class (Form) and the kid class (Triangle). 

Issues with Polymorphism 

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

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

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 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 slim the kind of objects, which implies 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. 

Typically the improper design of a mother or father 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 techniques and language. 

Principally, the explanation for the delicate base drawback is that the developer of the bottom class has no thought of the subclass design. There isn’t a resolution but for this drawback. 

Conclusion

We hope you should have gotten a primary thought 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 study extra about programming and different associated ideas, try the programs on Nice Studying Academy and PG Applications in Software program Engineering.  

Additionally, in case you are getting 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. Preserve exploring and continue learning.

Continuously Requested Questions

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 direction of a profession on this subject, it is strongly recommended to discover the next pages in an effort to purchase a complete understanding of the event profession path: