Java Covariant Return Types - The Coding Shala

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Java Covariant Return Types

In Java 5.0 onward it is possible to override a method by changing the return type. The child's return type should be sub-type of parent's return type.
Java Covariant Return Types - The Coding Shala
Covariant return type refers to the return type of an overriding method. It works only for non-primitive return types.

Example of Covariant Return Type in Java

The following is a simple example of the covariant return type is java: 

//covariant return type example 
//thecodingshala.com 

class Parent{
    Parent Display(){
        System.out.println("Inside Parent's Display");
        return this;
    }
}

class Child extends Parent{
    Child Display(){
        System.out.println("Inside Child's Display");
        //can write also
        //return this;
        return new Child();
    }
}

class Main{
    public static void main(String[] args){
        Parent p1 = new Parent();
        p1.Display();
        
        Parent p2 = new Child();
        p2.Display();
    }
}
Output:
Inside Parent's Display
Inside Child's Display

we will see one more example of method overriding that explains covariant return types: 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

//Complete the classes below
class Flower {
    String whatsYourName(){
        return "I have many names and types";
    }
}

class Jasmine extends Flower{
    String whatsYourName(){
        return "Jasmine";
    }
}

class Lily extends Flower{
    String whatsYourName(){
        return "Lily";
    }
}

class Region {
    Flower yourNationalFlower(){
        return new Flower();
    }
}

class WestBengal extends Region{
    Jasmine  yourNationalFlower(){
        return new Jasmine();
    }
}

class AndhraPradesh extends Region{
    Lily yourNationalFlower(){
        return new Lily();
    }
}


public class Solution {
  public static void main(String[] args) throws IOException {
      BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
      String s = reader.readLine().trim();
      Region region = null;
      switch (s) {
        case "WestBengal":
          region = new WestBengal();
          break;
        case "AndhraPradesh":
          region = new AndhraPradesh();
          break;
      }
      Flower flower = region.yourNationalFlower();
      System.out.println(flower.whatsYourName());
    }
}



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