Covariant returns

[Sathya Shanmugam]

Hi folks,

Could any give more examples for covariant returns, Any link would be appreciated..


thanks

[Sathya Shanmugam]

And also like to have some explanation with example for the following statement from KB book

" Overriding methods can do so only within the bounds of covariant returns"...

[Chandra Bhatt]

Hi Sathya,

" Overriding methods can do so only within the bounds of covariant returns"...

   
class Animal {
 
Animal meth() {
    return new Animal();
}
 
public String toString() {
    return "Animal Object";
}
}
 
class Dog extends Animal {
 
     Dog meth() {
          return new Dog();
     }
 
     public String toString() {
         return "Dog Object";
     }
 
    public static void main(String... args) {
          Animal ani = new Dog();
          System.out.println(ani.meth());
    }
}
 
Output: Dog Object
 

 

New Thing to learn: You may have heard of bridge method; How does JVM handle to call the overridden method with covariant return type; The compiler automatically inserts the following in the subclass(in out example)

Animal meth() {
return this.meth();
}


Hope you got the concept!

Thanks & Regards,
cmbhatt

[Sathya Shanmugam]

Thanks chan for your immediate reply

I don't know what is a bridge method :roll: