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Interview Questions and Answers for 'Cerner' - 21 question(s) found - Order By Newest

Very frequently asked. Among first few questions in almost all interviews. Among Top 5 frequently asked questions. Frequently asked in Indian service companies (HCL,TCS,Infosys,Capgemini etc based on multiple feedback ) and Epam Systems
  Q1. Difference between == and .equals() ?Core Java
Ans. "equals" is the method of object class which is supposed to be overridden to check object equality, whereas "==" operator evaluate to see if the object handlers on the left and right are pointing to the same object in memory.

x.equals(y) means the references x and y are holding objects that are equal. x==y means that the references x and y have same object.

Sample code:

String x = new String("str");
String y = new String("str");

System.out.println(x == y); // prints false
System.out.println(x.equals(y)); // prints true

  Sample Code for equals

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   Like         Discuss         Correct / Improve     java   string comparison   string   object class   ==    equals   object equality  operator   == vs equals   equals vs ==     Asked in 294 Companies      basic        frequent

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  Q2. 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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   Like         Discuss         Correct / Improve     oops  oops features     Asked in 260 Companies      basic        frequent


Very frequently asked. Favorite question in Walk in Drive of many Indian service companies.
  Q3. What is the difference between ArrayList and LinkedList ?Core Java
Ans. Underlying data structure for ArrayList is Array whereas LinkedList is the linked list and hence have following differences -

1. ArrayList needs continuous memory locations and hence need to be moved to a bigger space if new elements are to be added to a filled array which is not required for LinkedList.

2. Removal and Insertion at specific place in ArrayList requires moving all elements and hence leads to O(n) insertions and removal whereas its constant O(1) for LinkedList.

3. Random access using index in ArrayList is faster than LinkedList which requires traversing the complete list through references.

4. Though Linear Search takes Similar Time for both, Binary Search using LinkedList requires creating new Model called Binary Search Tree which is slower but offers constant time insertion and deletion.

5. For a set of integers you want to sort using quicksort, it's probably faster to use an array; for a set of large structures you want to sort using selection sort, a linked list will be faster.

  Sample Code for ArrayList

  Sample Code for LinkedList

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   Like         Discuss         Correct / Improve     collections   java   data structures   arraylist   linkedlist   arraylist vs linkedlist     Asked in 61 Companies      Basic        frequent

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Basic and Very Frequently asked.
  Q4. What is Polymorphism in Java ?Core Java
Ans. Polymorphism means the condition of occurring in several different forms.

Polymorphism in Java is achieved in two manners

1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas

2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding.

  Sample Code for overloading

  Sample Code for overriding

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   Like         Discuss         Correct / Improve     polymorphism  object oriented programming (oops)  oops concepts  oops concepts     Asked in 108 Companies      Basic        frequent

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Very frequently asked. Favorite question in Walk in Drive of many Indian service companies.
  Q5. What is a final method ?Core Java
Ans. Its a method which cannot be overridden. Compiler throws an error if we try to override a method which has been declared final in the parent class.

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   Like         Discuss         Correct / Improve     java   oops   final   final method     Asked in 30 Companies      basic        frequent

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Very Frequently asked across all type of companies and across all levels.
  Q6. Difference between Public, Private, Default and Protected ?Core Java
Ans. Private - Not accessible outside object scope.

Public - Accessible from anywhere.

Default - Accessible from anywhere within same package.

Protected - Accessible from object and the sub class objects.

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   Like         Discuss         Correct / Improve     java   oop   access specifier   public   private   default   protected   public vs private vs default vs protected     Asked in 12 Companies      basic        frequent

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Frequently asked to fresh graduates and less experienced.
  Q7. Difference between Composition and Inheritance ?Core Java
Ans. Inheritance means a object inheriting reusable properties of the base class. Compositions means that an abject holds other objects.

In Inheritance there is only one object in memory ( derived object ) whereas in Composition , parent object holds references of all composed objects.

From Design perspective - Inheritance is "is a" relationship among objects whereas Composition is "has a" relationship among objects.

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   Like         Discuss         Correct / Improve     java   oops   oops concepts   inheritance  object oriented programming (oops)  oops concepts   composition  object oriented programming (oops)  oops concepts   difference between   basic interview question     Asked in 12 Companies      basic        frequent

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Very frequently asked. Usually asked in different variants like Diff between StringBuffer , String Builder ; Difference between StringBuilder and String class; Choice between these classes etc.
  Q8. What is the difference between StringBuffer and String class ?Core Java
Ans. A string buffer implements a mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls.

The String class represents character strings. All string literals in Java programs, such as "abc" are constant and implemented as instances of this class; their values cannot be changed after they are created.

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   Like         Discuss         Correct / Improve     java   string   stringbuffer   frequently asked     Asked in 18 Companies      basic        frequent

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  Q9. Difference between Vector and ArrayList ?Core Java
Ans. Vectors are synchronized whereas Array lists are not.

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   Like         Discuss         Correct / Improve     java   basic interview question   vector   arraylist   collections   synchronization   vector vs arraylist     Asked in 35 Companies      basic        frequent


Very frequently asked. Usually difference between String,StringBuffer and StringBuilder is asked in different variations.
  Q10. Difference between StringBuffer and StringBuilder ?Core Java
Ans. StringBuffer is synchronized whereas StringBuilder is not.

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   Like         Discuss         Correct / Improve     java   string   stringbuffer   string class   stringbuilder   synchronized   basic interview question   infosys technologies     Asked in 17 Companies      basic        frequent

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 Q11. What is race condition ?Operating System
Ans. A source of possible errors in parallel programming, where one thread can cause an error in another thread by changing some aspect of the state of the program that the second thread is depending on (such as the value of variable).

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   Like         Discuss         Correct / Improve     java.threads   multithreading   race condition   parallel programming   synchronization   ebay   concurrency     Asked in 10 Companies


  Q12. What is JSON ?Json
Ans. JSON is "JavaScript Object Notation", primarily used for client-server or server-server communication. Its a much lighter and readable alternative to XML. JSON is language independent and is easily parse-able in all programming languages.

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   Like         Discuss         Correct / Improve     json   markup language   client server communication     Asked in 26 Companies      basic        frequent

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Frequently asked in CTS ( Based on 2 feedback )
  Q13. What is the difference between comparable and comparator in java.util pkg?Core Java
Ans. Comparable interface is used for single sequence sorting i.e.sorting the objects based on single data member where as comparator interface is used to sort the object based on multiple data members.

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   Like         Discuss         Correct / Improve     java   java.util   comparable   comparator   collections     Asked in 23 Companies      basic        frequent


  Q14. Explain the challenging problems you faced recently and how you overcame it ?General
Ans. [Open Ended Answer]

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   Like         Discuss         Correct / Improve     elsevier   open ended questions   overstock.com   cerner     Asked in 15 Companies        frequent


 Q15. Explain TDD or Test Driven Design ?Design
Ans. TDD is a development process that involves short iterations: first an automated test case is written. Then, the code is written to pass that test, and finally one refactors the new code to acceptable standards.

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   Like         Discuss         Correct / Improve     elsevier   test driven design ( TDD )   software development methodologies     Asked in 3 Companies        frequent


 Q16. Explain Agile Software Development Methodology ?Process
Ans. https://en.wikipedia.org/wiki/Agile_software_development

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   Like         Discuss         Correct / Improve     software development process  agile     Asked in 5 Companies        frequent


 Q17. Scale yourself on Java on the scale of 1 to 10General
Ans. [Open Ended Answer]

The objective of the question is to check how efficient one is in the language so that appropriate level questions are asked. Don't tell too high number if you are being interviewed for a junior or mid level position as the interviewer may throw advance level questions.

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   Like         Discuss         Correct / Improve          Asked in 17 Companies


  Q18. 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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   Like         Discuss         Correct / Improve     oops  oops concepts     Asked in 16 Companies      basic        frequent


  Q19. What is collection framework in Java ?Core Java
Ans. The Java collections framework (JCF) is a set of classes and interfaces that implement commonly reusable collection data structures. Although referred to as a framework, it works in a manner of a library. The JCF provides both interfaces that define various collections and classes that implement them.

  Sample Code for Map

  Sample Code for HashMap

  Sample Code for Treemap

  Sample Code for set

  Sample Code for hashset

  Sample Code for treeset

  Sample Code for list

  Sample Code for arraylist

  Sample Code for linkedlist

  Sample Code for queue

  Sample Code for priorityqueue

  Sample Code for concurrenthashmap

  Sample Code for vector

  Sample Code for stack

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   Like         Discuss         Correct / Improve     collections     Asked in 9 Companies      basic        frequent


 Q20. What is MVC in GUI components ?Design
Ans. The Model/View/Controller pattern, a strategy for dividing responsibility in a GUI component.

The model is the data for the component.

The view is the visual presentation of the component on the screen.

The controller is responsible for reacting to events by changing the model.

According to the MVC pattern, these responsibilities should be handled by different objects.

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   Like         Discuss         Correct / Improve     mvc  design pattern     Asked in 1 Companies        rare


 Q21. 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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   Like         Discuss         Correct / Improve          Asked in 23 Companies



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