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

Interview Questions and Answers - Order By Rating

Q1261. What is the advantage of using static final or constant variables in Java ?

Ans. Better Control - If the value is being used at multiple locations , that can be controlled better from single place. Any change would only require making single change.

Meaning , Aliasing and Better Readability - Sometimes its easy to read the value by its meaning or alias ( 0 as ZERO or 0 as NEUTRAL_VALUE ).

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Q1262. What could be the problems due to the usage of static methods and elements ?

Core Java

Ans. static methods and static elements are shared by all objects of a class and hence could create problem.

Static methods are not synchronized by default and hence could create problem when accessed through multiple threads. Static elements are shareable by class and hence state of one object could be altered by another object.

Some limitations with Unit testing as not all mocking framework facilitate mocking them. Power mock allows but Mockito doesn't

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Q1263. What is Maven ?

Maven

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

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Q1264. What is Spring Boot ?

Spring Boot

Ans. Spring Boot is Springs convention-over-configuration solution for creating stand-alone, production-grade Spring-based Applications.

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Q1265. 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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Q1266. Write a Program to print the positive and negative numbers separetly

Core Java

Ans. int[] arr = {1,-1,2,-3,3,-4,4,5,6,-5,-6,-7,-8,8,9,-9};
List positiveNumbers = new ArrayList<>();
List negativeNumbers = new ArrayList<>();
for(int i = 0; i < arr.length(); i ){
if(I < 0){
negativeNumbers.add(i);
} else {
positiveNumbers.add(i);
}
}

System.out.println("Positive Numbers:" + positiveNumbers);
System.out.println("Negative Numbers:" + negativeNumbers);

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Q1267. What are Collection Classes ?

Core Java

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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Q1268. Which method of String class is used to convert Boolean to String ?

Core Java

Ans. toString() is an overloaded method of String class that is used to convert many data types to String, Boolean being one of them.

toString(Boolean bool)

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Q1269. Is null a dataype ?

Core Java

Ans. It is special literal. It is neither keyword nor identifier.

Any reference in java that doesnt point to any object , gets assigned null i.e is a reference to null

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Q1270. What are fields that gets displayed when you execute "Top" command and briefly explain each field ?

Unix

Ans. PID - process identification number is an identification number that is automatically assigned to each process when it is created

USER - User Name

PR - PR is the process actual priority

NI is the nice value, which is a user-space concept.

VIRT -Virtual Image (kb). The total amount of virtual memory used by the task.

RES - Resident size (kb). The non-swapped physical memory a task has used.

SHR - Shared Mem size (kb). The amount of shared memory used by a task.

S - Process Status. The status of the task which can be one of:

D = uninterruptible sleep
R = running
S = sleeping
T = traced or stopped
Z = zombie

%CPU - % CPU usage

%MEM - % MEM Usage

TIME - Total CPU time the task has used since it started.

COMMAND - Command which was used to execute the process

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Q1271. Write a unix command to find top 10 files by size ?

Unix

Ans. du -a /var | sort -n -r | head -n 10

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Q1272. What will be the crontab to run a job every last day of month ?

Unix

Ans. 59 23 28-31 * * [ "$(date +%d -d tomorrow)" = "01" ] && job_name

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Frequently asked in Accenture.

Q1273. What is your biggest achievement at work ?

General

Ans. [Open Ended Answer]

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Q1274. Difference between Error and Exception ?

Core Java

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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Q1275. Difference between Array and ArrayList ?

Core Java

Ans. <a href="http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html" rel="nofollow">http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html</a>

Sample Code for ArrayList

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_{Like Discuss Correct / Improve array arraylist Asked in 11 Companies basic frequent}

Q1276. Write a Program to print permutations of a String.

Core Java

Ans. public static Stream permutations(String str) {
if (str.isEmpty()) {
return Stream.of("");
}

return IntStream.range(0, str.length()).boxed()
.flatMap(i -> permutations(str.substring(0, i) str.substring(i 1)).map(t -> str.charAt(i) t));

}

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Q1277. Write a Program to reverse a Linked List ?

Data Structure

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

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Q1278. Flatten a Binary Tree to Linked List

Algorithm

Ans. https://www.geeksforgeeks.org/flatten-a-binary-tree-into-linked-list/

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Q1279. Design a Data Structure for a full text Search ?

Design

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

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Q1280. What is the difference between http and https ?

Java EE

Ans. https encrypts the data using SSL whereas http sends it as plain text, So https is secure protocol whereas http is not.

Moreover https connects on port 443, while HTTP is on port 80

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Q1281. What is a web service ?

Java EE

Ans. A Web service is a service offered by one system to another, for communication over web through http. XML are JSON are usually used for sending across information from one system to another.

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Q1282. How would you process a 20 gb file with an application only having access to 4gb memory ?

BigData

Ans. Load the file in chunks and then process. If we need to do analytic, we can process analytic information for those chunks and then reprocess the processed information from each chunk.

For example - we need to average all marks in the file. We can divide the file and load into 5 chunks and calculate average for each chunk. Then we can collect averages for all 5 chunks and then calculate the final average.

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Q1283. Difference between relational databases and NoSQL databases ?

Database

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

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Q1284. Design an online shopping site system ?

Design

Ans. AWS Services - CloudFront for distribution / caching, EC2 for computing, EBS for block storage , S3 for object storage , RDS for database , Kinesis for streaming , CloudWatch for monitoring.

Technologies - Java for back end with Spring Boot , Angular , RxJs for front end .

Architecture - Service Oriented. Multi layer.

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Frequently asked in Alibaba (Based on 2 feedback)

Q1285. What is the best Memory setting for JVM ?

Core Java

Ans. In Java JVM memory settings is done by use the arguments -Xms -Xmx. Use M or G after the numbers for indicating Megs and Gigs of bytes respectively. -Xms indicates the minimum and -Xmx the maximum.

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Q1286. Can you write a "Hello World" program without using any ";" within it?

Core Java

Ans. Yes, That is possible

class A {
public static void main(String args[]){
if(System.out.printf("Hello World")==null){}
}
}

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Q1287. Difference between JDBC and Hibernate ?

Database

Ans. JDBC is a standard Java Api for Database communication whereas Hibernate is an ORM framework that uses JDBC to connect with Database.

Hibernate is another layer of object table mapping over JDBC that provide a database independent, object oriented and an efficient way of database communication.

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

Q1288. How is Hashmap internally implemented in Java ?

Core 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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Q1289. If everything is an object , Cant we declare every object as

Object obj = new String();

Core Java

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.

Q1290. Describe some of the Design Patterns you have used ?

Design

Ans. [Open Ended Answer]

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