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

Interview Questions and Answers for 'System' - 127 question(s) found - Order By Rating

Q1. what are system calls

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Q2. Difference between System.getEnv and System.getProperties ?

Core Java

Ans. System.getEnv gets the environment variables where System.getProperties gets Java properties.

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Q3. Write a calculator and find if a character appears more than n times ?

Design

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Q4. Pascal Triangle Program

Ans. package snippet;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Pascal {
   public static void main(String[] args) {

      System.out.println(generatePascalTriangle(5));

   }

   static Map> generatePascalTriangle(int size) {
      Map> triangle = new HashMap<>();

      triangle.put(0, Arrays.asList(1));
      triangle.put(1, Arrays.asList(1, 1));

      for (int i = 2; i <= size; i ) {
         List coeffListForI = new ArrayList<>();
         List coeffListForI_1 = triangle.get(i - 1);
         coeffListForI.add(1);
         for (int j = 0; j <= coeffListForI_1.size() - 2; j ) {
            coeffListForI.add(coeffListForI_1.get(j) coeffListForI_1.get(j 1));
         }
         coeffListForI.add(1);
         triangle.put(i, coeffListForI);
      }

      return triangle;
   }
}

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Q5. Explain Hibernate caching mechanism

Hibernate

Ans. Every fresh session having its own cache memory, Caching is a mechanism for storing the loaded objects into cache memory. The advantage of cache mechanism is, whenever again we want to load the same object from the database then instead of hitting the database once again, it loads from the local cache memory only, so that the no. of round trips between an application and a database server got decreased. It means caching mechanism increases the performance of the application.

In hibernate we have two levels of caching

First Level Cache [ or ] Session Cache
Second Level Cache [ or ] Session Factory Cache [ or ] JVM Level Cache

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Q6. What is Thread scheduler ?

Operating System

Ans. Thread Scheduler is the Operating System service that allocates the CPU time to the available runnable threads.

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Q7. What is Time slicing with respect to Threads ?

Operating System

Ans. Time Slicing is the process to divide the available CPU time to the available runnable threads.

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Q8. What sets you apart from other developers ?

or

What are the distinguished qualities you have ?

General

Ans. https://blog.timesunion.com/careers/the-10-most-important-personality-traits-for-career-success/633/

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Q9. Explain OAuth.

Authentication

Ans. OAuth is an open-standard authorization protocol or framework that describes how unrelated servers and services can safely allow authenticated access to their assets without actually sharing the initial, related, single logon credential. Like using Google or Facebook to login to something.

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Q10. What is OSGI ?

OSGI

Ans. OSGI is open service gateway initiative, its used as java framework for developing and deploying the modular softwares.

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Q11. Write code to sort an array.

Algorithm

Ans. https://www.geeksforgeeks.org/arrays-sort-in-java-with-examples/

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Q12. Difference between sleep() and Wait()

Operating System

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Q13. What is optimistic and pessimistic locking ?

Operating System

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Q14. What methodology and technology stack do you use ?

General

Ans. [Open Ended Answer]

Possible Answer - We are using Agile. We have daily standups, Bi weekly Backlog Grooming , Planning and Retrospective, We have a 2 week sprint and We use Jira for Scrum Management. We are using Java 8, Spring Boot, JSF , Apache Kafka , Soap as well as Rest Services.

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Q15. Why do you want to leave your current job ?

General

Ans. The most effective and acceptable reasons for leaving your current job should be positive e.g. moving forward in your life or career

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Q16. How to Create Cron Job in Hybris e-commerce suite

Hybris

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Q17. Explain OOps concepts.

Core Java

Ans. There are four main OOP concepts in Java. These are:

Abstraction. Abstraction means using simple things to represent complexity. We all know how to turn the TV on, but we don?t need to know how it works in order to enjoy it. In Java, abstraction means simple things like objects, classes, and variables represent more complex underlying code and data. This is important because it lets avoid repeating the same work multiple times.

Encapsulation. This is the practice of keeping fields within a class private, then providing access to them via public methods. It?s a protective barrier that keeps the data and code safe within the class itself. This way, we can re-use objects like code components or variables without allowing open access to the data system-wide.

Inheritance. This is a special feature of Object Oriented Programming in Java. It lets programmers create new classes that share some of the attributes of existing classes. This lets us build on previous work without reinventing the wheel.

Polymorphism. This Java OOP concept lets programmers use the same word to mean different things in different contexts. One form of polymorphism in Java is method overloading. That?s when different meanings are implied by the code itself. The other form is method overriding. That?s when the different meanings are implied by the values of the supplied variables. See more on this below.

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Q18. Difference between Class Path and Build Path ?

Core Java

Ans. The build path is used for building your application. It contains all of your source files and all Java libraries that are required to compile the application.

The classpath is used for executing the application. This includes all java classes and libraries that are needed to run the java application.

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Q19. Solve the producer and consumer problem

Operating System

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Q20. Explain OOPs

or

Explain OOPs Principles

or

Explain OOPs Concepts

or

Explain OOPs features

or

Tell me something about OOPs

Core Java

Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features

1. Inheritance for Code Reuse
2. Abstraction for modularity, maintenance and agility
3. Encapsulation for security and protection
4. Polymorphism for flexibility and interfacing

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Very frequently asked. Usually among very first few questions.

Q21. Define encapsulation in Java ?

Core 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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Q22. 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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Q23. 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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Q24. 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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Q25. What is the difference between CountingSemaphore and a CountDownLatch?

Operating System

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Q26. What is Livelock in relation to deadlock ?

Operating System

Ans. Livelock is when two threads or processes get deadlocked because they try to perform the same action to come out of a potential deadlock.

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Q27. What are the four situations that are required for deadlock to happen ?

Operating System

Ans. mutual exclusion i.e the resource is not shareable and hence a process should have exclusive access to it at a particular time

Hold and Wait i.e the process doesn't release all existing resources held by it before requesting for another one.

No preemption i.e noone can forcefully release a resource held by another process and the process should voluntarily release the resource held by it.

Circular Wait - For ex, P1 is waiting on resource to be released by P2, P2 is waiting on resource to be released by P3 and P3 is waiting on the resource to be released by P1

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Q28. Write a class and override the equals and hashcode method ?

Core Java

Ans. class Student
{
///
///
///
private int id;
private String name;

///
///
///
public Student(int id, String name)
{
this.name = name;
this.id = id;

}// Student

///
///
///
public int getId()
{
return id;

}// getId

///
///
///
public void setId(int id)
{
this.id = id;

}// setId

///
///
///
public String getName()
{
return name;

}// getName

///
///
///
public void setName(String name)
{
this.name = name;

}// setName

@Override
public boolean equals(Object obj)
{
if (obj == null) return false;
if (!(obj instanceof Student))
return false;
if (obj == this)
return true;

return this.getId() == ((Student) obj).getId();

}// equals

///
///
///
@Override
public int hashCode()
{
return this.getId();

}// hashCode

}// Student

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Q29. What is JVM ?

Core Java

Ans. JVM (Java Virtual Machine) is an abstract machine. It is a specification that provides runtime environment in which java bytecode can be executed.JVMs are available for many hardware and software platforms (i.e. JVM is platform dependent).Runtime Instance Whenever you write java command on the command prompt to run the java class, an instance of JVM is createdThe JVM performs following operation:Loads codeVerifies codeExecutes codeProvides runtime environment

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Q30. why should one we use 32 bit system instead of 64 bit?

Operating System

Ans. Performance of a system doesn't solely rely on size of processor or it's communication size. It should also be compatible with other resources like memory, storage etc. Moreover it makes no sense to have 64 bit systems when there is hardly any software than can run on 64 bit system.

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