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

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Q91. Which immutable classes have you worked with ? Can you name some immutable Collections ? How to make an immutable collection ?

Core Java

Ans. string and wrapper class objects

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Q92. What is the difference between Singleton and Prototype Bean scope in Spring ?

Spring

Ans. Prototype scope - A new object is created each time it is injected/looked up. It will use new SomeClass() each time.

Singleton scope - It is the default scope. The same object is returned each time it is injected/looked up. Here it will instantiate one instance of SomeClass and then return it each time.

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Q93. Explain Generics in Java ?

Core Java

Ans. Generics are a facility of generic programming that were added to the Java programming language in 2004 within J2SE5.0. They allow "a type or method to operate on objects of various types while providing compile-time type safety.

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Q94. Write code to find second largest number in an array of integers.

Core Java

Ans. int arr[]={1,3,5,6,4,8,9,2,10};
Arrays.sort();
System.out.println(arr[arr.length-1]);

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Q95. Write a Program to find age by birth date ?

Core Java

Ans. LocalDate today = LocalDate.now();
LocalDate birthday = LocalDate.of(1960, Month.JANUARY, 1);
Period p = Period.between(birthday, today); //Now access the values as below
System.out.println(period.getDays());
System.out.println(period.getMonths());
System.out.println(period.getYears());

Sample Code for LocalDate

Sample Code for Period

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Q96. Difference between constructor and setter injection ?

Spring

Ans. 1. In Setter Injection, partial injection of dependencies can possible, means if we have 3 dependencies like int, string, long, then its not necessary to inject all values if we use setter injection. If you are not inject it will takes default values for those primitives1. In constructor injection, partial injection of dependencies cannot possible, because for calling constructor we must pass all the arguments right, if not so we may get error

2. Setter Injection will overrides the constructor injection value, provided if we write setter and constructor injection for the same property [i already told regarding this, hope you remember ] But, constructor injection cannot overrides the setter injected values

3. If we have more dependencies for example 15 to 20 are there in our bean class then, in this case setter injection is not recommended as we need to write almost 20 setters right, bean length will increase. In this case, Constructor injection is highly recommended, as we can inject all the dependencies with in 3 to 4 lines [i mean, by calling one constructor]

4. Setter injection makes bean class object as mutable [We can change ] .Constructor injection makes bean class object as immutable [We cannot change ]

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Q97. 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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Q98. What is Amazon EC2 ?

Amazon Web Services (AWS)

Ans. Amazon Elastic Compute Cloud or EC2 provides scalable computing capacity in the AWS cloud. It can be used to create Virtual Environments , storage and configure. EC2 enables to upgrade or downgrade infrastructure according to the rules defined ( with fluctuation in latency, traffic etc )

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Q99. Where does database stored procedures gets stored ?

Database

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

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Q100. Is synchronized a keyword , modifier, identifier? what is it ?

Core Java

Ans. synchronized is a keyword and a modifier. The synchronized keyword is used to indicate that a method can be accessed exclusively by one thread at a time.

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Q101. What is the use of constructors in Java ?

Core Java

Ans. Constructors are used to initialize the state of an object. If there are no constructor , objects won't have any initialized state and hence it's elements may contain garbage values. If the memory were used as is, the behavior of the object would also be unpredictable.

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Q102. Find the third last element in a linked list ?

Data Structure

Ans. First Find the number of nodes in the linked list and take it as n.then find the data at n-3 element.

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Q103. Write a program for 0 and cross games?

Core Java

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

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Q104. Write a Program to merge two sorted arrays ?

Data Structure

Ans. We can merge two sorted array by using quick sort algorithm

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Q105. 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.

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Q106. Given 2 jars of 5 ltr and 3 ltr, how will you get 4 ltrs in one of those jars ?

Puzzle

Ans. Number 1 -

Fill the 5 litre can from the tap

Empty the 5 litre can into the 3 litre can leaving 2 litres in the 5 litre can.

Pour away the contents of the 3 litre can.Fill the 3 litre can with the 2 litres from the 5 litre can leaving 2 litres in the 3 litre can.

Fill the 5 litre can from the tap.Fill the remaining 1 litre space in the 3 litre can from the 5 litre can.Leaving 4 litres in the 5 litre can.

Number 2 -

Fill the 3 litre can from the tap.Empty the contents of the 3 litre can into the 5 litre can.

Fill the 3 litre can from the tap.Empty the contents of the 3 litre can into the 5 litre can leaving the 5 litre can full and 1 litre in the 3 litre can.

Pour away the contents of the 5 litre can. Pour the 1 litre from the 3 litre can into the 5 litre can.

Fill the 3 litre can from the tap. Empty the contents of the 3 litre can into the 5 litre can leaving 4 litres in the 5 litre can.

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Q107. How do threads share information ?

Core Java

Ans. Through common memory area.

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Q108. Write program to create a linked list and perform different operations on it.

Algorithm

Ans. import java.util.*;
class LinkedListSolution{
protected LinkedList list;
public LinkedListSolution(){
list = new LinkedList();
}
public Object pop() throws NoSuchElementException{
if(list.isEmpty())
throw new NoSuchElementException();
else
return list.removeFirst();
}
public void push(Object obj){
list.addFirst(obj);
}
public Object peek() throws NoSuchElementException{
if(list.isEmpty())
throw new NoSuchElementException();
else
return list.getFirst();
}
public boolean isEmpty(){
return list.isEmpty();
}
public String toString(){
return list.toString();
}
}
class TestStack{
public static void main(String args[]){
LinkedListSolution s = new LinkedListSolution();
s.push("First");
s.push("Second");
s.push("Third");
System.out.println("Top: " s.peek());
s.push("Fourth");
while(!(s.isEmpty()))
System.out.println(s.pop());
}
}

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Q109. 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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Q110. What is an execution engine within JVM ?

Core Java

Ans. Execution engine contains interpreter and JIT compiler, which covert byte code into machine code.

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Q111. 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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Q112. What are the core OOPs concepts ?

Core Java

Ans. Abstraction, Encapsulation, Polymorphism , Composition and Inheritance

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Frequently asked Spring interview question.

Q113. What are the components of Spring framework ?

Spring

Ans. Core: [Core, Bean, Context, Expression Language]

Web: [Web, Portlet, Servlet, etc]

Data Access [JMS, JDBC, etc]

AOP, Aspect

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Q114. 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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Q115. 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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Q116. Write a Program to print duplicate words in a String

Core Java

Ans. public class BuggyBread {
public static void main(String args[]) {
String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
Set<String> words = new HashSet();
for(String word:str.split(" ")){
if(words.contains(word)){
System.out.println(word);
} else {
words.add(word);
}
}
}
}

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Q117. What are the different primitive data types in Java ?

Core Java

Ans. boolean
byte
char
double
float
int
long
short
void

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Q118. Write a Program / Code showing Inheritance and overridding

Core Java

Ans. class A {
public void test() {
System.out.println("Class A Test");
}
}

class B extends A {
public void test() {
System.out.println("Class B Test");
}

public static void main(String[] args){
A a = new B();
a.test(); // will print Class B Test
}
}

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Q119. Write Code showing Inheritance

Core Java

Ans. class A {
public void test() {
System.out.println("Class A Test");
}
}

class B extends A {
public void test() {
System.out.println("Class B Test");
}
}

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Q120. Write a Program to print count of each character in a String.

Core Java

Ans. public class BuggyBread {
public static void main(String args[]) {
Map<Character, Integer> countMap = new HashMap();
String str = "hello world";
for (char character : str.toCharArray()) {
if (countMap.containsKey(character)) {
countMap.put(character, countMap.get(character) + 1);
} else {
countMap.put(character, 1);
}
}
System.out.println(countMap);
}
}

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