Interview Questions and Answers for 'Ato' | Search Interview Question

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

Q1. What is SNMP ?

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 15 Companies}

Q2. How many heaps will be there with 3 threads ?

Core Java

Ans. All threads share a common heap.

Each thread has a private stack, which it can quickly add and remove items from. This makes stack based memory fast, but if you use too much stack memory, as occurs in infinite recursion, you will get a stack overflow.

Help us improve. Please let us know the company, where you were asked this question :

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

Q3. How to write an iterator for an iterator of iterators?

Core Java

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;
      }

   }

}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve iterator Asked in 1 Companies}

Q4. Difference between Route53 aliasis and cname ?

Amazon Web Services (AWS)

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

Help us improve. Please let us know the company, where you were asked this question :

_{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)

Ans. Route 53

Help us improve. Please let us know the company, where you were asked this question :

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

Q6. Where to use interface and abstract class ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 2 Companies}

Q7. How to sort objects based on one of the field ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

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

Q8. Difference between == and === ?

JavaScript

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

Help us improve. Please let us know the company, where you were asked this question :

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

Q9. What is the access time for ArrayList and LinkedList ?

Data Structure

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 2 Companies}

Q10. What is garbage collection ?

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 4 Companies}

Q11. Design ATM machine application using oops.

Design

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q12. Can we modify a list while iterating it ?

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

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

Q13. Explain OOps concepts.

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve oops oops concepts Asked in 16 Companies basic frequent}

Q14. Explain what happens when insertion is performed in case of ArrayList and LinkedList.

Data Structure

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.

Help us improve. Please let us know the company, where you were asked this question :

_{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 Java

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.

Help us improve. Please let us know the company, where you were asked this question :

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

Q16. Why doesn't java support operator overloading ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve operator overloading}

Q17. What is a ternary operator ?

Database

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

Help us improve. Please let us know the company, where you were asked this question :

_{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 Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve oops oops features Asked in 260 Companies basic frequent}

Usually asked in relation to casting and ClassCastException.

Q19. What is instanceOf operator ? Explain it's use ?

Core Java

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();
}

Help us improve. Please let us know the company, where you were asked this question :

_{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 Java

Ans. >=

=> will result in error.

=> somewhat looks like lambda operator "->"

Help us improve. Please let us know the company, where you were asked this question :

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

Q21. What is the difference between Enumeration and Iterator ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve enumeration vs iterator collections Basic frequent}

Q22. Explain OOPS.

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 2 Companies}

Q23. Why do we need Garbage collection ?

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

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

Q24. What is a mutator in Java?

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve setter method mutator}

Q25. What is the precedence of operators in Java ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve operators operator precedence basic}

Q26. Where do you see yourself in next 5 years?

General

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.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 2 Companies}

Q27. What are the core OOPs concepts ?

Core Java

Ans. Abstraction, Encapsulation, Polymorphism , Composition and Inheritance

Help us improve. Please let us know the company, where you were asked this question :

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

Q28. What is the difference between && and & in Java ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve operators logical vs bitwise operator}

Q29. What are the different operators in Java ?

Core Java

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

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve operators Basic}

Q30. Explain dot(.) operator ?

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve operators}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.