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Q1221. In the following code, which text will get printed immediately after Hello

for(int countx=0;countx<10;count++){
System.out.println("World");
for(int countx=0;countx<10;count++){
System.out.println("Friend");
for(int countx=0;countx<10;count++){
System.out.println("Hello");
break;
}
System.out.println("Buddy");
}
}

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Q1222. Which of the two - iteration or recursion - is slower ?

Ans. Any function call is slower than the code in the same method as Java has to maintain stack of meta and function call information. So recursion is slower.

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Q1223. In case of generic class declared like following , What can T hold

class MyClass<T>{
T element;
}

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Q1224. What features would you like to see in Java 10 ?

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Q1225. Can we instantiate the object of derived class if parent constructor is private ?

Ans. No

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Q1226. Can an enum extend another enum ?

Ans. No

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Q1227. Can we have a sub enum within an enum ?

Ans. Yes

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Q1228. If a Map needs to be accessed simultaneously by multiple threads, which collection class should be used ?

Ans. ConcurrentHashMap

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Q1229. Given a collection of Employee objects, how can we get the customers with name starting with 'A' using lambda expression.

Ans. List emp = Arrays.asList("American", "Indian", "Finn");
emp.stream().filter(em -> em.startsWith("A")).forEach(System.out.println);

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Q1230. What is the difference between stream and parallel stream ?

Ans. streams are used for sequential processing of data and parallel streams are used for parallel processing of data (only if the underlying processor is multicore).

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Q1231. What are the advantage of Abstract classes over interfaces with respect to Java 7 ? and What changed in Java 8 to help facilitate that in Java 8 ?

Ans. Abstract Classes provide default implementations of methods that are inherited by the classes that extend them, which was not the case for Interfaces. This changed in Java 8, where default implementations are provided for methods.

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Q1232. Why do we use Thread Class as well as Runnable Interface for creating threads in Java ?

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Q1233. Why can we have a static inner class but not a static Top level class in Java ?

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Q1234. Write a Program to print fibonacci series using recursion.

Ans. public class FibonacciUsingRecursion {
   public static void main(String[] args) throws IOException{
      getNextFibanocci(1,1);
   }

   static int getNextFibanocci(int a,int b){
      if(a+b >= 100){
         return 0;
      } else {
         System.out.println(a+b);
         getNextFibanocci(b,a+b);
      }

      return 0;
   }
}

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Q1235. Can we use primitive types with Collection classes ?

Ans. No, As collection classes involve use of Generics, they cannot accept primitive types.

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Q1236. Is immutability an advantage with Wrapper classes over primitive types ?

Ans. There is no concept of de referencing with primitive types and hence they are implicitly immutable. Having wrapper classes as mutable offers disadvantages compared to primitive types. Wrapper classes being immutable offer similar advantage as primitive types.It actually overshadows the disadvantage wrapper class could have if they are immutable.

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Q1237. Do we have Integer constant pool of primitive int or Integer objects ?

Ans. It's of Integer objects and not primitive int.

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Q1238. Which objects are eligible for garbage collection ?

Ans. Objects that have lost their reference i.e. they cannot be accessed/used by the program anymore.

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Q1239. Do we have sorted collection for List ?

Ans. Not in java.util

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Q1240. What is a BlockingQueue ?

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Q1241. Which immutable classes have you worked with ? Can you name some immutable Collections ? How to make an immutable collection ?

Ans. string and wrapper class objects

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Q1242. What are the benefits of immutability or Immutable classes ?

Ans. Immutable objects are thread-safe so you will not have any synchronization issues.Immutable objects are good for Map keys and Set elements, since these typically do not change once created.Immutability makes it easier to write, use and reason about the code (class invariant is established once and then unchanged)Immutability makes it easier to parallelize your program as there are no conflicts among objects.The internal state of your program will be consistent even if you have exceptions.References to immutable objects can be cached as they are not going to change.

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Q1243. How is LinkedList collection class internally implemented ? Is it a Linked List or Doubly Linked List ?

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Q1244. How ConcurrentHashMap provides better performance compared to HashTable ?

Ans. ConcurrentHashMap uses multiple buckets to store Data and hence avoid read locks which facilitates better performance.

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Q1245. What are annotations and what are it's advantages ?

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Q1246. Suppose we have a string "Java is object oriented language" and we have to reverse every alternate word in string. How would we do that using Java program.

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Q1247. How to convert array to list in Java ?

Ans. We can use Arrays.asList

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Q1248. How much by default filling ratio in HashMap ?

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Q1249. Can we override wait() or notify() ?

Ans. No, because these are final.

public final void wait() throws InterruptedException

public final void notify()

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Q1250. What is a double ended queue?

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