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

Interview Questions and Answers for 'Epam' - 38 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 ) and Epam Systems

Q1. Difference between == and .equals() ?

Core Java

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

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

_{Like Discuss Correct / Improve java string comparison string object class == equals object equality operator == vs equals equals vs == Asked in 294 Companies basic frequent}

Try 6 Question(s) Test

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

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

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

_{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) inheritance vs composition object oriented programming (oops) oops concepts Asked in 29 Companies basic frequent}

Try 5 Question(s) Test

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

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

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

_{Like Discuss Correct / Improve java oops final finally finalize final vs finally vs finalize Asked in 61 Companies basic frequent}

Try 4 Question(s) Test

Very Frequently asked to fresh graduates and less experienced. Favorite question in Walk in drives. Frequently asked in Indian Services companies.

Q4. Difference between Overloading and Overriding ?

Core Java

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

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

_{Like Discuss Correct / Improve java oops overloading overriding oops concepts basic interview question overloading vs overriding Asked in 86 Companies basic frequent}

Try 1 Question(s) Test

Frequently asked in Cognizant ( Based on 2 feedback )

Q5. What are Inner , Outer , Left and Right Joins in SQL ?

Database

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.

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

_{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.

Q6. What are the methods of Object Class ?

Core Java

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.

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

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

Try 1 Question(s) Test

Q7. Difference between Static and Singleton Class ?

Core Java

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.

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

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

Very frequently asked in companies using SOA.

Q8. What are RESTful Web Services ?

Rest

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.

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

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

Frequently asked question for intermediate developers. Frequently asked in HCL Technologies and EPAM.

Q9. What is Volatile keyword used for ?

Core Java

Ans. Volatile is a declaration that a variable can be accessed by multiple threads and hence shouldnt be cached.

Sample Code for volatile

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

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

Try 1 Question(s) Test

Q10. What is a stream and what are the types of Streams and classes of the Streams?

Core Java

Ans. A Stream is an abstraction that either produces or consumes information. There are two types of Streams :

Byte Streams: Provide a convenient means for handling input and output of bytes.

Character Streams: Provide a convenient means for handling input & output of characters.

Byte Streams classes: Are defined by using two abstract classes, namely InputStream and OutputStream.

Character Streams classes: Are defined by using two abstract classes, namely Reader and Writer.

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

_{Like Discuss Correct / Improve java file io streams byte stream character stream file handling Asked in 3 Companies}

Q11. Difference between Factory and Builder Design Pattern ?

Design

Ans. Builder pattern is the extension of Factory pattern wherein the Builder class builds a complex object in multiple steps.

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

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

Q12. What is reflection ?

Ans. It is the process of examining / modifying the behaviour of an object at runtime.

Sample Code for reflection

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

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

Very Frequently asked.

Q13. Explain throw, throws , try and catch in Java ?

Core Java

Ans. throw is used to re throw an exception.throws is used to declare that the method throws the respective exceptions.try block is used to identify if the respective block has thrown any exception.catch is used to catch the exception that has been thrown by the respective try block.

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

_{Like Discuss Correct / Improve java exception handling throw throws try catch Asked in 5 Companies basic frequent}

Q14. What is coupling and Cohesion ?

Design

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.

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

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

Q15. 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.

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

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

Q16. What are design situations to use Singleton and Prototype Design Pattern ?

Design

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.

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

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

Try 1 Question(s) Test

Q17. When is the situation when finally section won't execute ?

Core Java

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

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

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

Try 1 Question(s) Test

Q18. What is the use of static keyword in Java ?

Core Java

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.

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

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

Q19. Find different combination of given String and trace the output

Core Java

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");

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

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

Q20. Difference between List and LinkedList ?

Core Java

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

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

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

Very frequently asked. Usually followed by questions related to private constructor and synchronized access. Frequently asked in JPMorgan and TCS (Based on 2 feedback)

Q21. Explain Singleton Design Pattern ?

Design

Ans. http://www.buggybread.com/2014/03/java-design-pattern-singleton-interview.html

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

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

Q22. Have you ever had any conflict with the team member (like disagreement on some design decision ) and How you reacted to it ?

General

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.

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

_{Like Discuss Correct / Improve Asked in 20 Companies basic}

Q23. How to make sure that only one instance is created in Singleton Pattern ?

Core Java

Ans. public class SingleTon {
private SingleTon() {
if (singleTon != null) {
throw new RuntimeException("cant not create the object");
}
}
public Object clone() throws CloneNotSupportedException {
throw new CloneNotSupportedException("can not be create");
}

static private volatile SingleTon singleTon;
public static SingleTon getInstance() {
SingleTon singleTon = this.sample;
if (singleTon == null) {
synchronized (this) {
singleTon = this.singleTon;
if (singleTon == null) {
singleTon = this.singleton = new SingleTon();
}
}
}
return singleTon;
}
}

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

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

Q24. What is an exception and exception handling in Java ?

Core Java

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.

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

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

Q25. What technical stuff you like to do in your free time ?

General

Ans. [Open Ended Answer]

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

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

Q26. What was the most difficult task in your last job ?

General

Ans. [Open Ended Answer]

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 would you do if a customer asks you to make a change immediately that require some time for thinking and analysis ?

General

Ans. [Open Ended Answer]

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

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

Q28. What is a factory design pattern ?

Design

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.

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

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

Q29. Given a 12-hour analog clock, compute in degree the smaller angle between the hour and minute hands

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

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

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

Q30. How is hashcode calculated in java ?

or

What are the rules for hashcode calculation ?

Core Java

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.

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

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

Search Interview Questions

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