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

Interview Questions and Answers - Order By Newest

Q1231. What happens when you assign a pre initialized reference some other object ?

Ans. Now the reference points to a new object in memory. If that was the only reference for the previous object , it will be marked for garbage collection.

Foe example -

Object obj = new Object();
obj = new Object();

object created in first line will be eligible for garbage collection after line 2 as it looses all it's handlers.

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Q1232. What is replication in Redis ? why do we need it ?

Redis

Ans. Asynchronous Replication of information from master to all slaves. Redis is an in memory storage and hence any crash may result in complete loss of information on a cluster.

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Q1233. What is the difference between Oracle , Cassandra and Redis ?

Database

Ans. Oracle is a relational database. Cassandra is a noSQL Database whereas Redis is an inmemory cache.

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Q1234. What are var args ?

or

What is the use of var args ?

Core Java

Ans. Var args is the feature of Java that allows a method to have variable number of arguments. Var args are used when we are not sure about the number of arguments a method may need. Internally java treats them as array.

Declarations of methods with var args

void method(int... x){};
void method(int x, int... y){};

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Q1235. Why following method declarations are not valid ?

void method(int... x, int y){};
void method(int... x,int... y){};

Core Java

Ans. Because var args are not only allowed with the last argument in the method declaration.

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Q1236. Which method will get called if we call it as method(1)

void method(int x ){};
void method(int... x){};

Core Java

Ans. Though the call an be bind to either of these but in this case, 1st method will get priority and hence will be called.

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Q1237. Can we catch errors in Java ?

Core Java

Ans. Yes we can

try {
// code
} catch (Error ex) {
// handling code
}

but we shouldn't ideally do that as errors are mostly JVM based and not application based and there is rarely we can do something about it. Very likely catching and not re throwing would lead to muting their response or trace.

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Q1238. Do you see any problem with this code

public class BuggyBread {

   public static void main(String[] args) {
      method("Hello","World");
   }

   private static void method(String... args){
      for(String arg:args){
         System.out.println(arg);
      }
   }
}

Core Java

Ans. No, It will compile and execute perfectly fine. As we are using method with var args , we can call it with 0 to n arguments.

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Q1239. Do you see any problem with this code

public class BuggyBread {

   public static void main(String[] args) {
      method();
   }

   private static void method(String... args){
      for(String arg:args){
         System.out.println(arg);
      }
   }
}

Core Java

Ans. This will compile fine as we can provide 0 arguments for a var arg but will print nothing upon execution.

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Q1240. Do you see any problem with this code

public class BuggyBread {

   public static void main(String[] args) {
      method("Hello");
   }

   private static void method(String... args){
      for(String arg:args){
         System.out.println(arg);
      }
   }

   private static void method(String arg){
      System.out.println(arg);
   }
}

Core Java

Ans. It will compile fine and the method call will bind to method with specific argument and not with var arg

i.e private static void method(String arg)

It will print "Hello" upon execution

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Q1241. Do you see any problem with this code

public class BuggyBread {

   public static void main(String[] args) {
      method("Hello");
   }

   private static void method(String... args){
      for(String arg:args){
         System.out.println(arg);
      }
   }

   private static void method(String[] arg){
      System.out.println(arg);
   }
}

Core Java

Ans. Yes, it will give compilation error and java will complain about duplicate method. Java treat var args internally as arrays and hence would result in same byte code for both method's syntax.

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Q1242. Will this code work

public class BuggyBread {

   public static void main(String[] args) {
      method("Hello","World");
   }

   private static void method(String[] arg){
      System.out.println(arg);
   }
}

What all possible changes we can make to method signature to make it work ?

Core Java

Ans. It won't work as java won't find the method definition for method with 2 arguments.

We can either declare the method as

private static void method(String arg,String arg2)

or

private static void method(String... arg)

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Q1243. What is a host file ?

Operating System

Ans. It's an operating system file that maps IP address to host names. The hosts file assists the OS in addressing networked components and serves the function of translating human friendly hostnames into numeric protocol addresses, called IP addresses, that identify and locate a host in an IP network.

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Q1244. What is the order in which triggers gets fired ?

Database

Ans. There is no specific order in which database fires the triggers if they are for the same operation. If we need to have a specific order for their execution, we should have them all in a stored procedure and the procedure should get executed upon the event.

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Q1245. How do you take screenshot in selenium?

Selenium

Ans. TakeScreenshot th = TakeScreenshot(driver); //Enable the driver object to take screenshot

File src = th.getScreenShotAs(OutputType.FILE);

FileUtils.copyFilesrc("locationWhereUWantToPlaceTheScreenshot.jpg");

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Q1246. What are the examples of immutable objects in Java ?

Core Java

Ans. Following Classes in Java SE creates immutable objects

String class
Wrapper Classes like Integer, Float etc.
StackTraceElement
Most Enum classes
File Class
Locale Class

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Q1247. Can you give real time examples of thread or where thread are actually used ?

Core Java

Ans. Games are very good examples of threading.You can use multiple objects in games like cars, motor bikes, animals, people etc. All these objects are nothing but just threads that run your game application.

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Q1248. What is meant by the statement "Java is turing complete" ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

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Q1249. What is Lambda Calculus ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

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Q1250. What is meant by "Locality of Reference" or "Cache Locality" ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

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Q1251. What is dynamic dispatch in Java ?

Core Java

Ans. Dynamic dispatch in java is also known as runtime polymorphism.It is a process in which a call to an overriden method is resolved at runtime.

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Q1252. why aren't arrays better than array list ?

Core Java

Ans. 1. Arrays don't provide any built in support for sorting searching like operation and we need to do it explicitly.

2. It can hold only homogeneous objects,

3. We have to reserve memory as no dynamic expansion allowed.

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Q1253. How many Windows are there in Manhattan ?

General

Ans. Population of Manhattan is roughly 2 millions. Nearly same number of people come to Manhattan daily for work. So if whole of Manhattan comprise of only residential and commercial buildings, that makes up 1/3rd residential and 2/3rd commercial. I have lived in a house in a high rise building in downtown and the average size of the house is 1 bedroom with 2 windows and on average 2 people live in a house. So that makes up roughly 1.33 million windows in Residential buildings. At commercial buildings, windows per capita is much lower as more people share the space and roughly it comes down to 1 window for 10 people. So that makes up .266 millions windows in commercial establishments.

So in total there are roughly 1.6 million windows in Manhattan.

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Q1254. 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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Q1255. What is the difference between latency, response time and processing time ?

Web Service

Ans. Latency is the delay incurred while communicating a message i.e the time took the message in transit over network.

processing time is the delay it took for the server to process the request.

Response time is the sum total of latency and processing time.

For example -

Let's say it takes 1 ms for the request to reach from client to server and similar 1 ms for the response to come back to client. Moreover it takes approx 10 ms for the application to process the request. So The response time would be outward latency + processing time + inward latency = 12 ms

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Q1256. What is the difference between Elastic Compute Cloud and Elastic Beanstalk ?

Amazon Web Services (AWS)

Ans. EC2 is Amazon computing service whereas Elastic Beanstalk is the AWS service for deploying and managing web applications.

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Q1257. How do you check logs for your application in AWS ?

Amazon Web Services (AWS)

Ans. We can do it by either going to Elastic Beanstalk -> Respective instance -> Logs

or using CloudWatch -> Logs -> Respective Log Group

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Q1258. What is AWS CloudWatch ?

Amazon Web Services (AWS)

Ans. Amazon CloudWatch is a monitoring service for AWS cloud resources like Beanstalk and DB instances. We can use CloudWatch to monitor the state of resources, collect metrices, set alarms and appropriate response to the alarm state.

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Q1259. What is Boxing conversion ?

Core Java

Ans. Boxing conversion converts expressions of primitive type to corresponding expressions of reference type.

For example

boolean to Boolean
long to Long
double to Double

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Q1260. Difference between Load Balancing and Failover Clustering ?

Server

Ans. Load Balancing is a provision to improve performance by reducing load on a single machine / server. Traffic or load is distributed among different machines and hence resulting in better performance / response time by leveraging more resources.

Failover is a provision to achieve better availability by switching to a backup server in case of failure.

Load Balancing aims as improving performance whereas failover aims at improving availability.

We can achieve both together by using a Load Balancing system which will isolate an instance in case of it's failure.

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