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Interview Questions and Answers for 'Epam' - 35 question(s) found - Order By Newest

Very frequently asked. Among first few questions in almost all interviews. Among Top 5 frequently asked questions. Frequently asked in Indian service companies (HCL,TCS,Infosys,Capgemini etc based on multiple feedback )
  Q1. Difference between == and .equals() ?Core Java
Anonymous
Ans. "equals" is the method of object class which is supposed to be overridden to check object equality, whereas "==" operator evaluate to see if the object handlers on the left and right are pointing to the same object in memory.

x.equals(y) means the references x and y are holding objects that are equal. x==y means that the references x and y have same object.

Sample code:

String x = new String("str");
String y = new String("str");

System.out.println(x == y); // prints false
System.out.println(x.equals(y)); // prints true

  Sample Code for equals

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   Like         Discuss         Correct / Improve     java   string comparison   string   object class   ==    equals   object equality  operator     Asked in 289 Companies      basic        frequent

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Frequently asked to fresh graduates and less experienced developers. Among the first few questions in many interviews.
  Q2. What are the difference between composition and inheritance in Java?Core Java
Admin
info@buggybread.com
Ans. Composition - has-a relationship between objects.
Inheritance - is-a relationship between classes.

Composition - Composing object holds a reference to composed objects and hence relationship is loosely bound.
Inheritance - Derived object carries the base class definition in itself and hence its tightly bound.

Composition - Used in Dependency Injection
Inheritance - Used in Runtime Polymorphism

Composition - Single class objects can be composed within multiple classes.
Inheritance - Single class can only inherit 1 Class.

Composition - Its the relationship between objects.
Inheritance - Its the relationship between classes.

  Sample Code for inheritance

  Sample Code for composition

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   Like         Discuss         Correct / Improve     java   java concepts   inheritance  object oriented programming (oops)  oops concepts   composition  object oriented programming (oops)  oops concepts   inheritance  object oriented programming (oops)  oops concepts vs composition  object oriented programming (oops)  oops concepts     Asked in 28 Companies      basic        frequent

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Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. Frequently asked in HCL Technologies, TCS and Accenture.
  Q3. What is the difference between final, finally and finalize() ?Core Java
Admin
info@buggybread.com
Ans. final - constant variable, objects cannot be de-referenced, restricting method overriding, restricting class sub classing.

finally - handles exception. The finally block is optional and provides a mechanism to clean up regardless of what happens within the try block. Use the finally block to close files or to release other system resources like database connections, statements etc.

finalize() - method helps in garbage collection. A method that is invoked before an object is discarded by the garbage collector, allowing it to clean up its state.

  Sample Code for final

  Sample Code for finally

  Sample Code for finalize

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   Like         Discuss         Correct / Improve     java   oops   final   finally   finalize     Asked in 60 Companies      basic        frequent

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Frequently asked in Cognizant ( Based on 2 feedback )
  Q4. What are Inner , Outer , Left and Right Joins in SQL ?Database2017-01-09 13:07:55

Ans. Inner join is the intersection of two tables on the condition defined by the where clause i.e will get records from both tables matched by a column.

Outer join is the union of two tables i.e will get all records from both tables and will put null in the columns where related records are not present.

Left Outer join is the left union of two tables i.e all records from the table on the left and values from the right table for related records else null for the columns from right table.

Right Outer join is the right union of two tables i.e all records from the table on the right and values from the left table for related records else null for the columns from left table.

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   Like         Discuss         Correct / Improve     sql  inner join  outer join  right join  left join     Asked in 24 Companies      basic        frequent


Frequently asked. Favorite question in Walk in Drive of many Indian service companies.
  Q5. What are the methods of Object Class ?Core Java
Anonymous
Ans. clone() - Creates and returns a copy of this object.

equals() - Indicates whether some other object is "equal to" this one.

finalize() - Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

getClass() - Returns the runtime class of an object.

hashCode() - Returns a hash code value for the object.

toString() - Returns a string representation of the object.

notify(), notifyAll(), and wait() - Play a part in synchronizing the activities of independently running threads in a program.

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   Like         Discuss         Correct / Improve     java   oops   object class     Asked in 16 Companies      basic        frequent

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 Q6. Difference between Static and Singleton Class ?Core Java2016-11-30 21:00:43

Ans. 1. Static class is a class which cannot be instantiated and all its members are static whereas Singleton is the class that only permit creation of single object and then the object is reused.

2. As there is no object in Static class, it cannot participate in runtime Polymorphism.

3. As Static class doesnt allow creating objects and hence it cannot be serialized.

4. Static class body is initialized eagerly at application load time whereas Singleton object can be initiated eagerly using static blocks or lazily on first need.

5. Its not recommended to use pure static class as it fails to use many OOPs concepts.

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   Like         Discuss         Correct / Improve     Static Class  Singleton  Static Class vs Singleton     Asked in 3 Companies      Intermediate        frequent


Very Frequently asked to fresh graduates and less experienced. Favorite question in Walk in drives. Frequently asked in Indian Services companies.
  Q7. Difference between Overloading and Overriding ?Core Java
Anonymous
Ans. Overloading - Similar Signature but different definition , like function overloading.

Overriding - Overriding the Definition of base class in the derived class.

  Sample Code for overloading

  Sample Code for overriding

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   Like         Discuss         Correct / Improve     java   oops   overloading   overriding   oops concepts   basic interview question     Asked in 82 Companies      basic        frequent

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Very frequently asked in companies using SOA.
  Q8. What are RESTful Web Services ?Rest
Admin
info@buggybread.com
Ans. REST or Representational State Transfer is a flexible architecture style for creating web services that recommends the following guidelines -

1. http for client server communication,
2. XML / JSON as formatiing language ,
3. Simple URI as address for the services and,
4. stateless communication.

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   Like         Discuss         Correct / Improve     java   web services   rest   java   j2ee  architecture     Asked in 14 Companies      intermediate        frequent


Frequently asked question for intermediate developers.
  Q9. What is Volatile keyword used for ?Core Java
Anonymous
Ans. Volatile is a declaration that a variable can be accessed by multiple threads and hence shouldnt be cached.

  Sample Code for volatile

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   Like         Discuss         Correct / Improve     java   oops   synchronization   volatile   java keywords     Asked in 42 Companies      intermediate        frequent

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  Q10. What is reflection ?
Anonymous
Ans. It is the process of examining / modifying the behaviour of an object at runtime.

  Sample Code for reflection

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   Like         Discuss         Correct / Improve     java   reflection   reflection api   ebay   mindtree     Asked in 29 Companies      basic        frequent


  Q11. What is coupling and Cohesion ?Design2016-11-15 16:16:10

Ans. Coupling is the degree of interdependence between software modules, a measure of how closely connected two modules are or the strength of the relationships between modules.

Cohesion refers to the degree to which the elements of a module belong together. Cohesion measures the strength of relationship between pieces of functionality within a given module.

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   Like         Discuss         Correct / Improve     coupling  cohesion     Asked in 10 Companies        frequent


 Q12. What is the use of static keyword in Java ?Core Java2017-01-09 13:32:24

Ans. static keyword is used to specify that the respective programming construct ( method , variable ) belongs to the class and not to its instance and is supposed to be shared by all instances of the class.

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   Like         Discuss         Correct / Improve     static keyword     Asked in 1 Companies      basic        frequent


 Q13. Find different combination of given String and trace the output

Core Java2018-01-21 17:14:13

Ans. private void permutation(String prefix, String sufix)
{
int ln = sufix.length();
if(ln == 0) {
System.out.println(prefix);
} else {
IntStream.range(0, ln).forEach(i->permutation(prefix sufix.charAt(i), sufix.substring(0,i) sufix.substring(i 1, ln)));
}
}

call:permutation("", "abcdef");

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   Like         Discuss         Correct / Improve     String  code  coding     Asked in 1 Companies


 Q14. Difference between List and LinkedList ?Core Java2019-07-13 15:33:49

Ans. A List is an child interface of collection interface in java where as Linked list is and implementation class of List interface which has doubly linked as a underlying data structure

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   Like         Discuss         Correct / Improve     linkedlist  list vs linkedlist     Asked in 1 Companies


 Q15. Difference between Factory and Builder Design Pattern ?Design
Anonymous
Ans. Builder pattern is the extension of Factory pattern wherein the Builder class builds a complex object in multiple steps.

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   Like         Discuss         Correct / Improve     java   design pattern   factory design pattern   builder design pattern     Asked in 1 Companies      expert


Very frequently asked. Usually followed by questions related to private constructor and synchronized access. Frequently asked in JPMorgan and TCS (Based on 2 feedback)
  Q16. Explain Singleton Design Pattern ?Design
Admin
info@buggybread.com
Ans. http://www.buggybread.com/2014/03/java-design-pattern-singleton-interview.html

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   Like         Discuss         Correct / Improve     java   design pattern   singleton   at&t   ebay  fidelity india  united healthcare india     Asked in 46 Companies      intermediate        frequent


 Q17. Which java frameworks have you used ?General

Ans. I have primarily worked on Web applications and hence worked on Struts , Spring , Hibernate, JSF ( Java Server Faces ) , Velocity etc.

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   Like         Discuss         Correct / Improve     elsevier   frameworks   java frameworks   general question     Asked in 3 Companies      basic        frequent


 Q18. Have you ever had any conflict with the team member (like disagreement on some design decision ) and How you reacted to it ? General2016-11-30 15:55:39

Ans. [Open Ended Answer]

This is a very sensitive question and should be dealt with caution. Just simply saying that you never had any disagreement will present you as dumb team member. Showing your self as too aggressive in such decisions will present you as a trouble maker. You should present a situation where you had an argument / disagreement but eventually you and your team mates mutually found a way out of it.

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   Like         Discuss         Correct / Improve          Asked in 20 Companies      basic


 Q19. What are design situations to use Singleton and Prototype Design Pattern ?Design2016-07-28 20:28:43

Ans. Both are creational design patterns.

Singleton is used when we would like to reuse an object if object is not supposed to hold request or thread specific information. Inversely Prototype is used in situations where we would like to reuse the object information but the request / thread may require it own data to be persisted.

In short, Singleton is used in situations where we can live with single object being shared across multiple requests or threads whereas Prototype is used when we need duplicate copies of objects.

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   Like         Discuss         Correct / Improve     design pattern  singleton  prototype  creational design pattrn     Asked in 7 Companies      expert

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 Q20. How to make sure that only one instance is created in Singleton Pattern ?Core Java2016-12-21 10:00:04

Ans. By Using Double Checked Locking code

//Double Checked Locking Code
public static Singleton createInstance() {
if(singleton == null){
synchronized(Singleton.class) {
if(singleton == null) {
singleton = new Singleton();
}
}
}
return singleton;
}

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   Like         Discuss         Correct / Improve     singleton  design pattern     Asked in 2 Companies


 Q21. When is the situation when finally section won't execute ?Core Java2017-01-09 12:56:46

Ans. If the process / app is abruptly killed or terminated.

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   Like         Discuss         Correct / Improve     exception handling  finally     Asked in 2 Companies      intermediate

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  Q22. What is an exception and exception handling in Java ?Core Java2017-01-09 13:01:40

Ans. An Exception in java is the occurrence during computation that is anomalous and is not expected.

Exception handling is the mechanism which is used to handle such situations.


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   Like         Discuss         Correct / Improve     exception handling     Asked in 18 Companies      basic        frequent


 Q23. What technical stuff you like to do in your free time ?General2017-01-09 13:14:13

Ans. [Open Ended Answer]

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   Like         Discuss         Correct / Improve          Asked in 2 Companies        frequent


 Q24. What was the most difficult task in your last job ?General2017-01-09 13:15:20

Ans. [Open Ended Answer]

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   Like         Discuss         Correct / Improve          Asked in 2 Companies


 Q25. What would you do if a customer asks you to make a change immediately that require some time for thinking and analysis ?General2017-01-09 13:19:49

Ans. [Open Ended Answer]

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 Q26. What is a factory design pattern ?Design2017-01-09 13:21:43

Ans. Factory Design Patterns is the pattern that recommends creation of separate Factory Object for creation of other object.

So its like saying - If you want to create an object of ClassA, Talk to FactoryObject ( which is an object of FactoryClass ). FactoryObject in itself encapsulates the inputs and logic required to make the decision regarding the creation and construction of object.

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   Like         Discuss         Correct / Improve     design pattern  factory design pattern     Asked in 9 Companies


 Q27. Given a 12-hour analog clock, compute in degree the smaller angle between the hour and minute hands2017-01-09 13:25:15

Ans. Zero Degree. Because the hour and minute hands overlap once in an hour.

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 Q28. How is hashcode calculated in java ?

or

What are the rules for hashcode calculation ?
Core Java2017-01-09 13:27:25

Ans. General contract of hashCode is:

1.Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer,

2.If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.

3.It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results.

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   Like         Discuss         Correct / Improve     hashcode     Asked in 1 Companies      expert


 Q29. Find Max from Stack in O(1) complexityAlgorithm2018-01-21 17:13:23

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


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   Like         Discuss         Correct / Improve     complexity  stack  data structure     Asked in 1 Companies


 Q30. In the Following code which foo will get called.

foo(Integer i){
}

foo(String s){
}

public static void main(){
passing foo(null);
}
Core Java2018-01-21 17:16:39

Ans. ambiguity error

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 Q31. What are the ways to break singleton pattern ?Design2018-04-08 11:16:57

Ans. If we don't have double checked locking, it can be broken easily through multi threaded access.

Through Reflection.

If multiple class loaders are loading the class.

If the class is serializable or cloneable.


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   Like         Discuss         Correct / Improve     singleton     Asked in 2 Companies      expert


 Q32. What are the technologies you would like to work on ?General2019-07-13 15:32:31

Ans. Java 7 , SQL Server

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   Like         Discuss         Correct / Improve          Asked in 2 Companies


 Q33. Explain features of MongoDB.MongoDB2019-07-13 15:34:46

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


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   Like         Discuss         Correct / Improve          Asked in 1 Companies


 Q34. What is dynamic programming ?2019-07-13 15:34:58

Ans. Dynamic programming is as a problem solving approach in which problem is divided into simpler sub problems which are over lappping in nature and solved once. its results are stored into a suitable data structure and reused to solve bigger sub problems

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 Q35. How can we increase the speed of SQL queries ?Database2019-07-13 15:35:43

Ans. Using -
1. Prepared Statements
2. Using Indices
3. Using whereby clause only on indexed columns

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   Like         Discuss         Correct / Improve          Asked in 1 Companies




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