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

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Q91. What is JAXB ?

Ans. Stands for Java API for XML Binding. This standard defines a mechanism for writing out Java objects as XML and for creating Java objects from XML structures.

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Frequently asked in CTS ( Based on 2 feedback )

Q92. What is the difference between comparable and comparator in java.util pkg?

Core Java

Ans. Comparable interface is used for single sequence sorting i.e.sorting the objects based on single data member where as comparator interface is used to sort the object based on multiple data members.

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Q93. Difference between socket and servlet ?

Java EE

Ans. servlet is a small, server-resident program that typically runs automatically in response to user input.
A network socket is an endpoint of an inter-process communication flow across a computer network.

We can think of it as a difference between door and gate. They are similar as they both are entry points but they are different as they are put up at different areas.

Sockets are for low-level network communication whereas Servlets are for implementing websites and web services

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Q94. Advantage of Collection classes over Arrays ?

Core Java

Ans. Collections are re-sizable in nature. We can increase or decrease the size as per recruitment.
Collections can hold both homogeneous and heterogeneous data's.
Every collection follows some standard data structures.
Collection provides many useful built in methods for traversing,sorting and search.

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Q95. What is Maven's order of inheritance?

Maven

Ans. 1. parent pom
2. project pom
3. settings
4. CLI parameters

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Q96. What is a Mojo?

Maven

Ans. A mojo is a Maven plain Old Java Object. Each mojo is an executable goal in Maven, and a plugin is a distribution of one or more related mojos.

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Q97. Write a method to check if input String is Palindrome?

Core Java

Ans. private static boolean isPalindrome(String str) {

if (str == null)
return false;

StringBuilder strBuilder = new StringBuilder(str);

strBuilder.reverse();

return strBuilder.toString().equals(str);

}

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Q98. Why String is popular HashMap key in Java?

Core Java

Ans. Since String is immutable, its hashcode is cached at the time of creation and it doesnt need to be calculated again. This makes it a great candidate for key in a Map and its processing is fast than other HashMap key objects. This is why String is mostly used Object as HashMap keys.

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

Q99. 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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Q100. Write a Program to check if 2 strings are Anagrams ?

Core Java

Ans. public void checkIfAnagram(String str1,String str2){
boolean anagram = true;
for(char c:str1.toCharArray()){
if(!str2.contains(String.valueOf(c))){
System.out.println("Strings are Anagrams");
anagram = false;
}

if(anagram == true){
System.out.println("Strings are not Anagrams");
}
}
}

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Very frequently asked Hibernate interview question. Frequently asked in TCS ( based on 2 feedback )

Q101. What are different types of associations in Hibernate ?

Hibernate

Ans. There are 4 types of associations in Hibernate

One to One
One to Many
Many to One
Many to Many

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Very frequently asked if being interviewed for hibernate. Frequently asked in Tata Consultancy (TCS) and Overstock.com

Q102. Difference between load and get ?

Hibernate

Ans. If id doesnt exist in the DB load throws an exception whereas get returns null in that case.get makes the call to DB immediately whereas load makes the call to proxy.

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Q103. What are Default Methods ?

Core Java

Ans. With Java 8, We can provide method definitions in the Interfaces that gets carried down the classes implementing that interface in case they are not overridden by the Class. Keyword "default" is used to mark the default method.

Sample Code for interface default

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Q104. Can we use static method definitions in Interfaces ?

Core Java

Ans. Yes, Effective Java 8.

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Q105. What are some different logging levels for log4j ?

Log4j

Ans. DEBUG
ERROR
ALL
WARN
INFO
FATAL
OFF
TRACE
TRACE_INT
WARN

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Q106. Difference between jar , war and ear ?

Java EE

Ans. Jar is Java Archieve i.e compressed Class or Class / Java files.

War comprises of compressed Servlet class files,JSP FIles,supporting files, GIF and HTML files.

Ear comprise of compressed Java and web module files ( was files ).

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Q107. How are values passed in Java ? By value or reference ?

Core Java

Ans. Java only provides pass by value.

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Q108. 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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Q109. What was the driving force to introduce default methods in Interfaces wef from Java 8 ?

Core Java

Ans. Earlier any class implementing an interface was supposed to implement all methods declared in an interface. There was no place for optionally implementing all or subset of methods.Though we have abstract classes wherein we could have provided such a mechanism by declaring some methods as abstract while providing definition for some. But as Abstract classes have a body and are comparatively heavier than interfaces and interfaces associate closely to the concept of providing interfacing than abstract classes, Java might have though of providing optional implementation for default methods. This way same interface can be reused in variety of ways rather than making copies of an interface to suit different needs.

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Q110. 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.

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Frequently asked.

Q111. When does the finally block gets executed ?

Core Java

Ans. A finally block of code always executes, whether or not an exception has occurred.The only time finally won't be called is if you call System.exit() or if the JVM crashes first.

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Very Frequently asked to Senior Software Engineers or Developers.

Q112. Describe some of the Design Patterns you have used ?

Design

Ans. [Open Ended Answer]

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Q113. Does java supports operator overloading ?

Core Java

Ans. No

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Q114. What is database Normalization ?

Database

Ans. https://en.wikipedia.org/wiki/Database_normalization

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Q115. Is it a good practice to use Asterick(*) in import statement to load multiple packages with single import statement ?

Core Java

Ans. No, we should be lean in loading only packages which are required. Loading packages which are not being used result in memory overheads.

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Q116. What is the difference between authentication and authorization ?

Authentication

Ans. Authentication is the process of verifying the identity and credentials of the user to authenticate him into the system.

whereas

Authorization is the process by which access to a segment , method or resource is determined.

Authorization is usually a step next to authentication.

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Q117. 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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Q118. What is a Webdriver ?

Testing

Ans. Selenium WebDriver is a tool for automating web application testing.It helps in replicating the manual tester behavior like keyboard entry, mouse events etc and then matching the output against the expected.

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Q119. What is Amazon S3 ?

Amazon Web Services (AWS)

Ans. Amazon Simple Storage Service or S3 is object storage with a simple web service interface to store and retrieve any amount of data from anywhere on the web.

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Q120. How Marker interfaces works internally ?

Core Java

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

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