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Q1741. 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 ?

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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Q1742. 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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Q1743. What is the order in which triggers gets fired ?

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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Q1744. How do you take screenshot in 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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Q1745. What are the examples of immutable objects in 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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Q1746. Can you give real time examples of thread or where thread are actually used ?

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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Q1747. What is meant by the statement "Java is turing complete" ?

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Q1748. Is Java type Safe ?

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Q1749. What is Lambda Calculus ?

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Q1750. What is Type Inference ? Can you explain with respect to Java ?

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Q1751. What is meant by "Locality of Reference" or "Cache Locality" ?

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Q1752. What is dynamic dispatch in 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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Q1753. why aren't arrays better than array list ?

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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Q1754. Which are the reserved words in Java ?

Ans. All Keywords , modifiers ( public , static , final etc ) as well as non modifier keywords ( for, if,switch etc ) are reserved words in java and hence cannot be used as identifiers. Along with keywords , there are few literals that have predefined meaning and hence cannot be used as identifiers, these are true , false and null.

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Q1755. How many Windows are there in Manhattan ?

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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Q1756. 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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Q1757. What is the difference between latency, response time and processing time ?

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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Q1758. 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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Q1759. 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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Q1760. 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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Q1761. What is widening and narrowing conversion in Java ?

Ans. Conversion means that the expression / literal / value of one type getting converted to other type.

Widening conversion is the conversion from Type A to Type B where B requires a wider space than A. For example - int to long, float to double, char to String etc. As the value moves to a wider space, there is no loss of information.

Narrowing conversion is the conversion from Type A to Type B where B requires a narrower space space than A. For example - int to long, float to double, char to String etc.As the value moves to a narrower space, there is a loss of information.

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Q1762. What is Boxing conversion ?

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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Q1763. Difference between Load Balancing and Failover Clustering ?

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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Q1764. What happens to private variables during inheritance ?

Ans. Private variables are not inherited. They are simply ignored and not made part of the derived object body.

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Q1765. Can we declare a class private ?

Ans. We can declare an inner class as private and hence would be restricting it's access from outside. We cannot make outer class as private.

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Q1766. Why can't we declare on outer class as private ?

Ans. Making an outer class as private will make it inaccessible from anywhere and would make it useless.

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Q1767. How can we hide a class in Java ?

Ans. By encapsulating it within another class and declaring it private. In such a case, it will only be accessible through parent class or parent class object.

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Q1768. What is the use of final keyword ?

Ans. final keyword is a modifier that means differently when applied to variables, methods and classes.

1. Final variable cannot be changed once initialized
2. Final method cannot be overridden
3. Final class cannot be sub classed

Sample Code for final variable

Sample Code for final method

Sample Code for final class

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Q1769. How would you explain the statement "Java Programs are collection of objects" ?

Ans. Java Programs are collection of objects that communicates with each other to get a task accomplished. To add to those objects, there are common spaces ( static i.e common for objects belonging to a class ) that are used too.

We can visualize objects as departments of an organization in real world. Just like Task gets initiated in one department and then files are moved across different departments to get work done. In a similar fashion, a task is initiated in one object ( having main method ) and then information ( through POJOs / DTOs ) is moved across objects to accomplish a task.

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Q1770. Why iterators of an array list are fail fast ?

Ans. Because it's access isn't synchronized and hence access / modification by multiple threads may lead to inconsistent state.

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