Core Java - Interview Questions and Answers for 'Generics' | Search Interview Question

Core Java - Interview Questions and Answers for 'Generics' - 8 question(s) found - Order By Newest

Q1. What are concepts introduced with Java 5 ?

Core Java

Ans. Generics , Enums , Autoboxing , Annotations and Static Import.

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Q2. Is this a valid initialization ? Explain.

Collection<Collection> collection = new LinkedList<LinkedList>();

Core Java

Ans. No. It will result in a type mismatch error.

Collection<Collection> collection = new LinkedList<Collection>();

is a valid initialization as collection being reference of "Collection" class can hold object of derived Class "LinkedList" due to runtime Polymorphism. Runtime polymorphism is not applicable to type arguments.

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Q3. Which of the following syntax is correct ?import static java.lang.System.*;or static import java.lang.System.*;

Core Java

Ans. import static java.lang.System.*;

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Q4. Is it legal to initialize List like this ?

LinkedList l=new LinkedList();

Ans. No, Generic parameters cannot be primitives.

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Q5. Which of the following syntax are correct ?a. LinkedList<Integer> l=new LinkedList<int>();b. List<Integer> l=new LinkedList<int>();c. LinkedList<Integer> l=new LinkedList<Integer>();d. List<Integer> l = new LinkedList<Integer>();

Core Java

Ans. All are correct.

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Q6. What are Type Erasures in Java ?

Core Java

Ans. Type erasure applies to the use of generics. When generics are used, they're pre compiled into compile time checks and execution-time casts.

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Q7. Explain Generics in Java ?

Core Java

Ans. Generics are a facility of generic programming that were added to the Java programming language in 2004 within J2SE5.0. They allow "a type or method to operate on objects of various types while providing compile-time type safety.

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Q8. In case of generic class declared like following , What can T hold

class MyClass<T>{
T element;
}

Core Java

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

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