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Ans. Coding , Science and Mathematics has always fascinated me. I have curious mindset that continuously look for solutions.

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Q363. 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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Very frequently asked. Usually asked in this format or as difference with interfaces / concrete classes.

Q364. What is an abstract class ?

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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Q365. What is Spring Security ?

Spring

Ans. Spring Security is a powerful and highly customizable authentication and access control framework. It is the de facto standard for securing Spring-based applications.

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Frequently asked in Cognizant ( Based on 2 feedback )

Q366. What are Inner , Outer , Left and Right Joins in SQL ?

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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Q367. What is an exception and exception handling in 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.

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Q368. When is the situation when finally section won't execute ?

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

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Try 1 Question(s) Test

Q369. What is database Normalization ?

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

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Q370. Why java doesn't support multiple Inheritance ?

or

Explain Java Diamond Problem.

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

Ans. class A {
void test() {
System.out.println("test() method");
}
}

class B {
void test() {
System.out.println("test() method");
}
}

Suppose if Java allows multiple inheritance like this,

class C extends A, B {
}

A and B test() methods are inheriting to C class.

So which test() method C class will take? As A & B class test() methods are different , So here we would Facing Ambiguity.

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Q371. What is the difference between ServletConfig and ServletContext ?

Java EE

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Q372. What is the difference between following code segments

1.

try {
for(int i=0;i<100;i++){
calculate(i);
}
} catch (Exception ex) {
System.out.println("Error while processing")
}

and

2.

for(int i=0;i<100;i++){
try {
calculate(i);
} catch (Exception ex) {
System.out.println("Error while processing")
}
}

Ans. In first case the whole loop will terminate as soon as any exception happens in the method calculate ( assuming calculate method is not handling its exception and those are thrown back at the calling method )

In Second case exception will be caught for individual iteration and hence it wont break the loop and will continue for the next iteration.

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Q373. Which type of memory is cleaned / recovered by garbage collection - stack or heap ?

Ans. Heap memory.

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Q374. With a Table employee having columns Id,Name,ManagerEmployeeId, Write a SQL to find the Manager with maximum number of employees ?

Ans. Select Name from EMPLOYEE where ID in (Select ManagerEmployeeId from EMPLOYEE
Group By ManagerEmployeeId
order by count(Id)
LIMIT 1)

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Q375. What is serialVersionUID ?

Ans. Everytime an object is serialized the java serialization mechanism automatically computes a hash value by passing the meta information for the class. This id is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization

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Q376. What is Maven ?

Maven

Ans. Maven is a build automation tool used primarily for Java projects.

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Q377. Explain some of the http status codes you know ?

Java EE

Ans. 500 is Internal Server Error

404 is resource not found

400 is Bad Request

403 is Forbidden

401 is Unauthorized

200 is OK

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Q378. What are Collection Classes ?

Ans. Collections in java is a framework of classes that provides an abstracted data structure to store and manipulate the group of objects. Each class is unique in the way it stores , search , sort and modify the elements.

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Frequently asked in Accenture.

Q379. What is your biggest achievement at work ?

Ans. [Open Ended Answer]

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Q380. Difference between Error and Exception ?

Ans. An Error indicates serious problems that a reasonable application should not try to catch whereas

An Exception indicates conditions that a reasonable application might want to catch.

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Q381. Difference between relational databases and NoSQL databases ?

Ans. https://www.mongodb.com/scale/nosql-vs-relational-databases

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Frequently asked in high end product companies. Frequently asked in Deloitte.

Q382. How is Hashmap internally implemented in Java ?

Ans. https://medium.com/javarevisited/internal-working-of-hashmap-in-java-97aeac3c7beb#:~:text=HashMap%20internally%20uses%20HashTable%20implementation,the%20entries%20into%20the%20map.

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Q383. If everything is an object , Cant we declare every object as

Object obj = new String();

Ans. Yes, we can do that. Compiler wont complain. But using object reference we can only access methods which have been defined for object class i.e clone(), equals(), hashCode(), toString() etc.

We cannot access methods defined in String class or in any class in hierarchy between String and Object.

For example - we cannot do obj.append("abc") as it will now give compile time error.

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Very Frequently asked to Senior Software Engineers or Developers.

Q384. Describe some of the Design Patterns you have used ?

Design

Ans. [Open Ended Answer]

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Frequently asked Generic Question.

Q385. Why do you want to work for our company ?

Ans. [Open Ended Answer]

Usually answered stating your keen interest in the role offered and challenges and opportunities the role offers.

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Q386. Write a Program to check if 2 strings are Anagrams ?

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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Q387. Have you ever had any conflict with the team member (like disagreement on some design decision ) and How you reacted to it ?

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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Q388. Write an Algorithm for Graph Traversal ? The Graph has a loop.

Algorithm

Ans. Please not that all such questions can be easily answered through recursion.

Simple recursive implementation could be

traverse(root);

void traverse(Element element){
if(element.hasNext()){
traverse(element.next());
} else {
System.out.println(element);
}
}

but this algo / code lead to endless loop if there is a loop in graph traversal.

So you can keep a collection to keep track of which elements have laready been traversed

static List<Elements> listOfAlreadyTraversedElements = new ArrayList<Elements>();

main(){
traverse(root);
}

void traverse(Element element){
if(element.hasNext()){
traverse(element.next());
} else {
listOfAlreadyTraversedElements.add(element);
System.out.println(element);
}
}

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Q389. How Java is different than C/C++ in terms of memory allocation and de-allocation ?