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Q781. 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);
   }
}

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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Q782. 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);
   }
}

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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Q783. 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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Q784. 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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Q785. 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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Q786. 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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Q787. 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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Q788. 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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Q789. 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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Q790. 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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Q791. 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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Q792. 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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Q793. 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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Q794. 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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Q795. 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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Q796. 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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Q797. 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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Q798. 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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Very frequently asked. Usually among very first few questions.

Q799. Define encapsulation in Java ?

Ans. Encapsulation is a feature of OOP's that binds the data and it's associated methods together as a single unit and facilitate protection and data hiding by providing minimal interface to outside. For example - member variables are declared private and are accessed through public methods. Moreover we have private methods that can only be used internally and hence providing minimal interface to outside class through use of public methods.

Sample Code for encapsulation

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Q800. Solve the producer and consumer problem

Operating System

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

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Q801. Give an example of how Object Oriented Programming Concepts can be implemented.

Ans. You can implement encapsulation in Java by keeping the fields (class variables) private and providing public getter and setter methods to each of them. Java Beans are examples of fully encapsulated classes. Encapsulation in Java: Restricts direct access to data members (fields) of a class.

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Q802. What are the different types of loops in Java ?

Ans. for, while and do while

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Q803. What is an infinite loop ?

Ans. Infinite loop is a programming condition wherein the control goes into an infinite loop because the loop termination condition can never be met. For example -

for(int x=1;x>0;x++){
}

in this loop, with each increment the condition x > 0 will remain true till infinity.

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Q804. What is a ternary operator ?

Ans. Ternary operator , also called conditional operator is used to decide which value to assign to a variable based on a Boolean value evaluation. It is used as

condition ? value1 : value2

For example

int y = (x > 0) ? x:0; // assign x if it's greater than 0, else assign 0

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Q805. What is the difference between JDBC, Hibernate and ODBC ?

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

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Q806. Is String a Data type in Java ?

Ans. String is not a primitive type in java. Anything defined within double quotes like "abc" is an object of String class.

Sample Code for String

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Q807. Are char,String and Char data types in java ?

Ans. char is a primitive data type. String is a class. Char is a wrapper class for primitive char.

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Q808. What is the difference between Stack and Queue ?

Data Structures

Ans. Stack is based on Last in First out (LIFO) principle while a queue is based on FIFO (First In First Out) principle.

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Q809. Can we compile and execute a Java class without main method ?

Ans. No without main method can not be executed it will throw an error illegal start of type. Main method is the entry point of application.

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Q810. What is the problem we could face if we be very liberal with importing classes even if we are not using them ? For example

import java.util.*;
import java.io.*;

Ans. It makes application little heavy as we are importing classes that aren't required.

It creates class name conflicts as similar name classes might be available across different packages. In case of such conflicts, we will have to specify the package name with the class name at the time of it's usage.

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