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Interview Questions and Answers for 'Ato' - 69 question(s) found - Order By Rating

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 Q1. What is SNMP ?Networking2019-10-03 15:10:13

Ans. SNMP or Simple Network Management protocol is an application layer protocol for exchanging management information between network devices.


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   Like         Discuss         Correct / Improve          Asked in 15 Companies


 Q2. How many heaps will be there with 3 threads ?Core Java2019-02-02 15:24:13

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


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   Like         Discuss         Correct / Improve     memory management  heap memory     Asked in 1 Companies


 Q3. How to write an iterator for an iterator of iterators?Core Java2019-02-01 12:33:36

Ans. CustomArrayList myarrayList = new CustomArrayList();
      myarrayList.add("Value 1");
      myarrayList.add("Value 2");
      myarrayList.add("Value 3");
      
      for (String string : myarrayList) {
         System.out.println(string);
      }



package sample.utils;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class CustomArrayList implements Iterable {

   private ArrayList mylist = new ArrayList();

   public void add(T t) {
      this.mylist.add(t);
   }

   @Override
   public Iterator iterator() {
      return new CustomIterator(mylist);
   }

   class CustomIterator implements Iterator {

      private int indexPosition = 0;
      private List internalList;

      public CustomIterator(List internalList) {
         this.internalList = internalList;
      }

      @Override
      public boolean hasNext() {
         if (internalList.size() >= indexPosition 1) {
            return true;
         }
         return false;
      }

      @Override
      public E next() {
         E val = internalList.get(indexPosition);
         indexPosition ;
         return val;
      }

   }

}

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   Like         Discuss         Correct / Improve     iterator     Asked in 1 Companies


 Q4. Difference between Route53 aliasis and cname ?Amazon Web Services (AWS)2019-01-25 14:32:34

Ans. Cname doesn't support naked domain names whereas aliasis does.

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   Like         Discuss         Correct / Improve     aws route53     Asked in 3 Companies


 Q5. What is the name of DNS service provided by AWS ?Amazon Web Services (AWS)2019-01-16 14:41:02

Ans. Route 53

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   Like         Discuss         Correct / Improve     AWS DNS  aws Route 53     Asked in 4 Companies


 Q6. Where to use interface and abstract class ?Core Java2018-08-06 14:52:09

 This question was recently asked at 'Exterro,Equator Business Solutions'.This question is still unanswered. Can you please provide an answer.


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 Q7. How to sort objects based on one of the field ?Core Java2018-07-04 16:23:09

Ans. Using comparable and comparator and sorted collections like TreeSet or TreeMap.

or

use stream api from java 8 onwards which internally refers to comparable and comparator through lambda expressions

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   Like         Discuss         Correct / Improve     sort  sorting  comprator  comparable  treeset  treemap  sorting collections     Asked in 1 Companies      Basic        frequent


  Q8. Difference between == and === ?JavaScript2018-07-04 16:16:18

Ans. == compares values === is used in scripting languages for comparing two values as well as there data tpe. like in js,php.

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   Like         Discuss         Correct / Improve     ==  ===  == vs ===     Asked in 13 Companies      basic        frequent


 Q9. What is the access time for ArrayList and LinkedList ?Data Structure2018-05-23 19:18:48

Ans. O(1) for ArrayList
O(n) for LinkedList

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 Q10. What is garbage collection ?Core Java2018-05-13 07:44:17

Ans. The garbage collection is a facility wherein a program runs on the Java Virtual Machine which gets rid of objects, which are not being used by a Java application anymore. It is a form of automatic memory management and recollection.

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 Q11. Design ATM machine application using oops.Design2018-03-28 10:42:04

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


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   Like         Discuss         Correct / Improve          Asked in 1 Companies


 Q12. Can we modify a list while iterating it ?Core Java2018-01-30 18:25:33

Ans. No,we cannot.I t will give concurrentModificationExceptin error. It can be resolved by using ConcurrentClasses like ConcurrentHashMap,CopyOnWriteArrayList,BlockingQueue etc which are fail-safe and wont give exception.

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   Like         Discuss         Correct / Improve     collections  list  iterator     Asked in 1 Companies      basic


  Q13. Explain OOps concepts.Core Java2017-12-25 17:29:13

Ans. There are four main OOP concepts in Java. These are:

Abstraction. Abstraction means using simple things to represent complexity. We all know how to turn the TV on, but we don?t need to know how it works in order to enjoy it. In Java, abstraction means simple things like objects, classes, and variables represent more complex underlying code and data. This is important because it lets avoid repeating the same work multiple times.

Encapsulation. This is the practice of keeping fields within a class private, then providing access to them via public methods. It?s a protective barrier that keeps the data and code safe within the class itself. This way, we can re-use objects like code components or variables without allowing open access to the data system-wide.

Inheritance. This is a special feature of Object Oriented Programming in Java. It lets programmers create new classes that share some of the attributes of existing classes. This lets us build on previous work without reinventing the wheel.

Polymorphism. This Java OOP concept lets programmers use the same word to mean different things in different contexts. One form of polymorphism in Java is method overloading. That?s when different meanings are implied by the code itself. The other form is method overriding. That?s when the different meanings are implied by the values of the supplied variables. See more on this below.

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   Like         Discuss         Correct / Improve     oops  oops concepts     Asked in 15 Companies      basic        frequent


 Q14. Explain what happens when insertion is performed in case of ArrayList and LinkedList.Data Structure2017-10-26 15:52:53

Ans. Array List works on Array and when we add an element in middle of the list, Array List need to update the index of all subsequent elements. I the capacity is full, it even may need to move the whole list to a new memory location . Linked List works on Double linked list algorithm and all it has to do is to adjust the address of the previous and next elements.

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   Like         Discuss         Correct / Improve     arraylist vs linkedlist  collections  list     Asked in 2 Companies


 Q15. How can i split a linked list in two parts in java 8?Core Java2017-10-22 15:00:24

Ans. This can be done using a Spliterator.

LinkedList list = Arrays.asList("names","numbs","birds","animals");
Spliterator split1 = list.Spliterator();
Spliterator split2 = split1.Spliterator();

Now, the LinkedList is split into split1 and split2.
use split2 first then split1 to check the output.

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   Like         Discuss         Correct / Improve     java 8  parallel stream  spliterator     Asked in 1 Companies


 Q16. Why doesn't java support operator overloading ?Core Java2017-06-23 08:15:18

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


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   Like         Discuss         Correct / Improve     operator overloading


 Q17. What is a ternary operator ?Database2017-06-18 16:46:34

Ans. Ternary operator , also called conditional operator is used to decide which value to assign to a variable based on a Boolean value evaluation. It is used as

condition ? value1 : value2

For example

int y = (x > 0) ? x:0; // assign x if it's greater than 0, else assign 0

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   Like         Discuss         Correct / Improve     operator  ternary operator      Basic


  Q18. Explain OOPs

or

Explain OOPs Principles

or

Explain OOPs Concepts

or

Explain OOPs features

or

Tell me something about OOPs
Core Java2017-06-13 08:25:45

Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features

1. Inheritance for Code Reuse
2. Abstraction for modularity, maintenance and agility
3. Encapsulation for security and protection
4. Polymorphism for flexibility and interfacing

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Usually asked in relation to casting and ClassCastException.
 Q19. What is instanceOf operator ? Explain it's use ?Core Java2017-06-12 07:58:22

Ans. The operator instanceOf is used to verify if the specified object is the instance of specified class or interface.

Syntax if(x instanceOf ABC)

where x is an object reference and ABC could be a class name or interface name. The above statement will be true if x holds an object that is an instance of ABC or any of the child class of ABC or if x holds an object that implements ABC.

instanceOf operator is used to verify in case of downcasting. For ex -

DerivedClass extends BaseClass

x is the reference of BaseClass but holds DerivedClass object ( Polymorphism )

There is an operation that is defined in Derived Class, let's say derivedClassMethod()

We cannot call derivedClassMethod() directly using x as x is reference of BaseClass and not DerivedClass and hence can only access methods that are defined in BaseClass and overridden in derived class.

Though we can cast it to DerivedClass as following
((DerivedClass)x).derivedClassMethod();

But it may throw ClassCastException in case x doesn't hold an instance of DerivedClass at that point.

So before casting it to DerivedClass we may like to make sure that it is an instance of DerivedClass and hence won't throw ClassCastException.

So we make a check for it

if(x instanceOf DerivedClass) {
((DerivedClass)x).derivedClassMethod();
}

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   Like         Discuss         Correct / Improve     instanceOf  instanceOf operator  Why we need instanceOf operator  use of instanceOf operator     Asked in 2 Companies      Intermediate        frequent


 Q20. Which of the following is valid greater than and equal to operator in Java ?

>=
=>
Core Java2017-05-20 16:23:47

Ans. >=

=> will result in error.

=> somewhat looks like lambda operator "->"

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   Like         Discuss         Correct / Improve     operators  >= operator  greater than and equal to operator  comparison operators


 Q21. What is the difference between Enumeration and Iterator ?Core Java2017-05-07 15:22:08

Ans. Enumeration can iterate only legacy collections like Vector , HashTable and Stack whereas Iterator can iterate both legacy and non legacy collections.

Enumeration is less safer than Iterator

Enumeration is fail safe whereas Iterator is fail fast

Iterator allows for removal of element while traversal whereas Enumeration doesn't have remove method.

Enumerations were introduced in Java 1 whereas Iterators were introduced with Java 2

Enumerations have methods like hasMoreElements and nextElement whereas Iterators have methods like hasNext, next and remove

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 Q22. Explain OOPS.Core Java2017-04-20 19:58:24

 This question was recently asked at 'Acute Informatics,General Atomics'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve          Asked in 2 Companies


 Q23. Why do we need Garbage collection ?Core Java2017-03-27 08:44:06

Ans. Garbage collection mechanism frees up the memory that is no longer needed. In languages like C / C++ the deallocation needs to be done explicitly by the programmer and hence any leniency may result in memory leak. Garbage collection in java ensures that all unused memory is reclaimed and hence there are no memory leaks.Moreover it relieves the programmer from the hassle of carefully releasing all memory.

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   Like         Discuss         Correct / Improve     Garbage Collection  memory management     Asked in 2 Companies


 Q24. What is a mutator in Java?Core Java2017-03-10 09:45:05

Ans. Mutator is another name for setter methods, i.e the method allows for mutating the property of an object and eventually the state of the object.

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 Q25. What is the precedence of operators in Java ?Core Java2017-03-01 09:42:52

Ans. http://introcs.cs.princeton.edu/java/11precedence/

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 Q26. Where do you see yourself in next 5 years? General2017-02-14 10:34:55

Ans. Sample Answers -

Getting better with upcoming technologies and be a Lead developer.

In accordance with the company, working as a permenant employee.

Be an associate architect.


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   Like         Discuss         Correct / Improve          Asked in 2 Companies


  Q27. What are the core OOPs concepts ?Core Java2017-02-06 16:15:55

Ans. Abstraction, Encapsulation, Polymorphism , Composition and Inheritance

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   Like         Discuss         Correct / Improve     core oops concepts     Asked in 65 Companies      basic        frequent


 Q28. What is the difference between && and & in Java ?Core Java2017-02-03 08:30:47

Ans. && is a Logical whereas & is a bitwise operator

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 Q29. What are the different operators in Java ?Core Java2017-01-28 15:15:36

Ans. && - AND
|| - OR
! - LOGICAL NOT

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 Q30. Explain dot(.) operator ?Core Java2017-01-19 13:53:35

Ans. Its used to access the object properties using the object reference or class properties using the Class Name. Moreover its used to access the classes and Interfaces of a package.

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