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Interview Questions and Answers for 'Polymorphism' - 16 question(s) found - Order By Newest

 Q1. What are points to consider in terms of access modifier when we are overriding any method?Core Java
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Ans. 1. Overriding method can not be more restrictive than the overridden method.

reason : in case of polymorphism , at object creation jvm look for actual runtime object. jvm does not look for reference type and while calling methods it look for overridden method.

If by means subclass were allowed to change the access modifier on the overriding method, then suddenly at runtime when the JVM invokes the true objects version of the method rather than the reference types version then it will be problematic

2. In case of subclass and superclass define in different package, we can override only those method which have public or protected access.

3. We can not override any private method because private methods can not be inherited and if method can not be inherited then method can not be overridden.

  Sample Code for Overriding

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   Like      Discuss      Correct / Improve     java   overriding   access specifier   inheritence   oops   polymorphism   runtime polymorphism     Genpact

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Basic and Very Frequently asked.
  Q2. What is Polymorphism in Java ?Core Java2016-11-06 09:10:54

Ans. Polymorphism means the condition of occurring in several different forms.

Polymorphism in Java is achieved in two manners

1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas

2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding.

  Sample Code for overloading

  Sample Code for overriding

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 Q3. If everything is an object , Cant we declare every object as

Object obj = new String();
Core Java2016-12-02 14:45:05

Ans. Yes, we can do that. Compiler wont complain. But using object reference we can only access methods which have been defined for object class i.e clone(), equals(), hashCode(), toString() etc.

We cannot access methods defined in String class or in any class in hierarchy between String and Object.

For example - we cannot do obj.append("abc") as it will now give compile time error.

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   Like      Discuss      Correct / Improve     object initialization  object declaration   runtime polymorphism


 Q4. Is this Polymorphism ?

Map<String, List<String>> inventoryManagerCountMap = new HashMap<String, ArrayList<String>>();
Core Java
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Ans. No. This will result in compilation error as Polymorphism cannot be performed on Object types.

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 Q5. When are static and instance methods resolved ? During compile time or Runtime ?
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Ans. Static methods are resolved during compile time and hence they cannot participate in runtime polymorphism. Instance methods are resolved during runtime.

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   Like      Discuss      Correct / Improve     java   static methods   methods   runtime polymorphism      intermediate


 Q6. Which of the following do you think is the primary reason you would never use a static class even the application doesn't need multiple requests or threads ?

a. Serialization
b. Runtime Polymorphism
c. Lazy Loading
d. Memory
Anonymous
Ans. Runtime Polymorphism

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   Like      Discuss      Correct / Improve     static class   static vs singleton   java   oops   objects  Runtime Polymorphism


 Q7. How is static and dynamic polymorphism achieved in Java ?Core Java

Ans. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding.

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   Like      Discuss      Correct / Improve     static polymorphism   dynamic polymorphism   polymorphism   overloading   overriding     Cognizant (CTS)      basic        frequent


 Q8. Why do we need polymorphism in Java ?Core Java2017-04-19 08:36:00

Ans. Frankly saying I dont see much use of method overloading as its just little design convenience as you can use the same name but still have binding to different methods depending on the need.

Method overriding is really important and is much more useful than method overloading. Along with other programming concepts like interfaces and dependency injection , it facilitates the development of software as libraries and plug-gable components.

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   Like      Discuss      Correct / Improve     Polymorphism


 Q9. Which of the two - compile time and run time polymorphism - requires signature of the method to be different ?Core Java2017-05-02 08:31:29

Ans. runtime polymorphism or method overriding doesn't require method name and signature to be different whereas compile time polymorphism or method overloading requires method name to be same but the signature to be different.

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   Like      Discuss      Correct / Improve     polymorphism  overloading  overriding      basic



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 Q10. How does java identifies which method to be called in method overriding or runtime polymorphism, when both methods share the same name and signature ? Core Java2017-05-02 08:33:52

Ans. Java identifies the method to be called at runtime by the object that is being referenced.

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   Like      Discuss      Correct / Improve     polymorphism  overloading  overriding      basic


 Q11. What is "dynamic method dispatch" in java ?Core Java2017-05-07 16:27:26

Ans. dynamic method dispatch is a process in which a call to an
overridden method is resolved at runtime rather than at compile-time. This is used to achieve runtime polymorphism in java.

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   Like      Discuss      Correct / Improve     overriding  runtime polymorphism


 Q12. What is dynamic dispatch in Java ?Core Java2017-05-29 09:57:31

 This question is still unanswered. Can you please provide an answer.


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   Like      Discuss      Correct / Improve     dynamic dispatch  runtime polymorphism


 Q13. Explain Inheritance and Polymorphism.Core Java2017-07-10 14:27:40

 This question was recently asked at 'Wipro'.This question is still unanswered. Can you please provide an answer.


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   Like      Discuss      Correct / Improve     inheritance  polymorphism     Wipro      Basic        frequent


 Q14. Is Runtime Polymorphism possible without Inheritance ?Core Java2017-08-06 19:12:26

Ans. Yes, Runtime Polymprohism requires either Class inheritance or Interface implementation.

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   Like      Discuss      Correct / Improve     runtime polymorphism  method overriding  inheritance


 Q15. Static Polymorphic in Java is achieved through .. Core Java
a. Method Overloading
b. Method Overriding
c. Variable Overloading
d. Variable Overriding

Ans.a. Method Overloading

 Q16. Runtime Polymorphism in Java is achieved through ..Core Java
a. Method Overloading
b. Method Overriding
c. Variable Overloading
d. Variable Overriding

Ans.b. Method Overriding



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