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

Interview Questions and Answers for 'Infor' - 44 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

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Advanced level question. Frequently asked in High end product companies. Frequently asked in Google , Cognizant and Deloitte ( Based on 2 feedback )

Q2. Why is String immutable in Java ?

Core Java

Ans. 1. String Pool - When a string is created and if it exists in the pool, the reference of the existing string will be returned instead of creating a new object. If string is not immutable, changing the string with one reference will lead to the wrong value for the other references.

Example -

String str1 = "String1";
String str2 = "String1"; // It doesn't create a new String and rather reuses the string literal from pool

// Now both str1 and str2 pointing to same string object in pool, changing str1 will change it for str2 too

2. To Cache its Hashcode - If string is not immutable, One can change its hashcode and hence it's not fit to be cached.

3. Security - String is widely used as parameter for many java classes, e.g. network connection, opening files, etc. Making it mutable might possess threats due to interception by the other code segment.

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Q3. 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

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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.

Q4. 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

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Basic and Very Frequently asked.

Q5. What is Polymorphism in Java ?

Core Java

Ans. Polymorphism means the condition of occurring in several different forms.

Polymorphism in Java is achieved in two manners

1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas

2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding.

Sample Code for overloading

Sample Code for overriding

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Frequently asked in Infosys India

Q6. What is a String Pool ?

Core Java

Ans. String pool (String intern pool) is a special storage area in Java heap. When a string is created and if the string already exists in the pool, the reference of the existing string will be returned, instead of creating a new object and returning its reference.

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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

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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Frequently asked to fresh graduates.

Q8. What is ACID ?

Database

Ans. ACID stands for Atomicity, Consistency, Isolation, Durability is a set of properties of database transactions.

Atomicity means all or nothing. i.e parts of a transaction shouldn't commit if any one of them fails. Either the whole transaction should succeed or it should be complete rollback.

Consistency means that any transaction should lead database from one stabe state to another.

Isolation means that the execution of transaction results in a system state that would be obtained if transactions were executed serially.

Durability means that when a transaction is committed it forms the permanent state of database.

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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

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Q10. Which of the following Java feature promotes access protection or Hiding ?

a. Inheritance
b. Encapsulation
c. Abstraction
d. Composition

Core Java

Ans. Encapsulation

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Q11. Why Java is not considered pure OOP's language ?

Core Java

Ans. There are 2 reasons for it.

1. Usage of Primitive types - Though Java provides classes for the primitive data types but as the usage of primitives is permissible, its considered unpure OOP's language.

2. Usage of Static members - Static members belong to the class and not objects and hence not considered fit for pure OOP's programming.

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Q12. Difference between Vector and ArrayList ?

Core Java

Ans. Vectors are synchronized whereas Array lists are not.

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Very frequently asked in phone and walk in interviews.

Q13. What are Marker Interfaces ? Name few Java marker interfaces ?

Core Java

Ans. An interface without any method declaration is called as marker interface. there are 3 in-built interfaces in JVM i.e. serializable, clonable, remote

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Q14. What is PermGen or Permanent Generation ?

Core Java

Ans. The memory pool containing all the reflective data of the java virtual machine itself, such as class and method objects. With Java VMs that use class data sharing, this generation is divided into read-only and read-write areas. The Permanent generation contains metadata required by the JVM to describe the classes and methods used in the application. The permanent generation is populated by the JVM at runtime based on classes in use by the application. In addition, Java SE library classes and methods may be stored here.

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Very frequently asked in HCL Tech ( Based of 4 inputs )

Q15. Write a program to reverse a string iteratively and recursively ?

Core Java

Ans. Using String method -

new StringBuffer(str).reverse().toString();

Iterative -

public static String getReverseString(String str){
StringBuffer strBuffer = new StringBuffer(str.length);
for(int counter=str.length -1 ; counter>=0;counter--){
strBuffer.append(str.charAt(counter));
}
return strBuffer;
}

Recursive -

public static String getReverseString(String str){
if(str.length <= 1){
return str;
}
return (getReverseString(str.subString(1)) + str.charAt(0);
}

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Q16. What is a self Join and give an example of a self Join ?

or

What is self Join and What is it's purpose ?

Database

Ans. When a Table Join itself , it's a Self Join. For example - we like to know the pair of department names where first dept has lesser employees than the later.

Select D1.name , D2.name from Dept D1, Dept D2 where D1.employee_count < D2.employee_count

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Q17. Write a Program to print factorial of a number using recursion

Core Java

Ans. public class BuggyBread {
public static void main(String args[]) {
System.out.println(factorial(5));
}

private static int factorial(int number){
if(number == 1){
return 1;
} else {
return number * factorial(number - 1);
}
}
}

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Q18. What is abstraction ?

Design

Ans. Abstraction is a process of hiding the implementation details and describing only the functionality to the user.

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Q19. What are the types of authentication used in Web services ?

Web Service

Ans. Encrypted User Name / Password
Encrypted Password within Cookie
Encrypted Tokens
IP
Client Certificates
Oauth

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Q20. What is concurrent interface ?

Core Java

Ans. ConcurrentMap is an interface and it is a member of the Java Collections Framework. It represents a Map that is capable of handling concurrent access to it without affecting the consistency of entries in a map. ConcurrentMap interface present in java.util.concurrent package.

HashMap operations are not synchronized, while Hashtable provides synchronization. Though Hashtable is thread-safe, it is not very efficient. To solve this issue, the Java Collections Framework introduced ConcurrentMap in Java 1.5.

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Very frequently asked. Usually asked in this format or as difference with interfaces / concrete classes.

Q21. What is an abstract class ?

Core Java

Ans. Abstract class is the class that is not supposed to be instantiated. The purpose of the class to only have extension to the derived class.

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Q22. What are the phases of the JSP life cycle ?

Java EE

Ans. Translation of JSP PageCompilation of JSP PageClassloading (class file is loaded by the classloader)Instantiation (Object of the Generated Servlet is created).Initialization ( jspInit() method is invoked by the container).Reqeust processing ( _jspService() method is invoked by the container).Destroy ( jspDestroy() method is invoked by the container).

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Q23. Difference between Abstraction and Implementation hiding ?

Ans. Implementation Hiding is a broader concept. Abstraction is a way of implementation hiding in OOP's.

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Frequently asked in face to face interviews.

Q24. Write a program to print fibonacci series.

Core Java

Ans. int count = 15;
int[] fibonacci = new int[count];
fibonacci[0] = 0;
fibonacci[1] = 1;
for(int x=2; x < count; x++){
fibonacci[x] = fibonacci[x-1] + fibonacci[x-2];
}

for(int x=0; x< count; x++){
System.out.print(fibonacci[x] + " ");
}

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Frequently asked to Fresh graduates.

Q25. Write a program to implement Binary search ?

Core Java

Ans. http://algs4.cs.princeton.edu/11model/BinarySearch.java.html

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Q26. What is a Database Procedure ?

Database

Ans. Stored procedures are a batch of SQL statements along with programming constructs ( if else, loops etc ) and stored as a single program that can be called by different clients and hence reused.

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Q27. What are some alternates to keeping Audit Tables ?

Database

Ans. Audit Tables generally stores Raw information to be reviewed in case of problems or determining impact. If Database space is an issue , and the audit information is rarely retrieved, one design could be to use compressed file system.

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Frequently asked in Accenture.

Q28. What is your biggest achievement at work ?

General

Ans. [Open Ended Answer]

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Q29. What is the difference between ServletConfig and ServletContext ?

Java EE

Ans. http://www.java4s.com/java-servlet-tutorials/difference-between-servletconfig-and-servletcontext-in-java/

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Q30. Is there any relationship between Web.xml and Spring.xml ?

Spring

Ans. No, there is no relationship between web.xml and spring.xml but you have to configure spring.xml in web.xml in order initialize beans when application starts up

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