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| Interview Questions and Answers for 'Deegit' - 13 question(s) found - Order By Rating | ||||
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| 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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 Discuss Correct / Improve  oops oops concepts  Asked in 16 Companies  basic  frequent | ||||
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| Ans. Abstraction is a process of hiding the implementation details and describing only the functionality to the user. | ||||
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| Discuss Correct / Improve bstraction oops concepts oops principle Asked in 22 Companies | ||||
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| 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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| Discuss Correct / Improve oops oops features Asked in 260 Companies basic frequent | ||||
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| Ans. https://en.wikipedia.org/wiki/Agile_software_development | ||||
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 Very Frequently asked across all type of companies and across all levels. | ||||
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| 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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| 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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| Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. | ||||
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| 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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| Discuss Correct / Improve java oops final final method Asked in 30 Companies basic frequent | ||||
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| Frequently asked to fresh graduates and less experienced. | ||||
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| Ans. Inheritance. | ||||
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| Discuss Correct / Improve inheritance object oriented programming (oops) oops concepts java oops composition object oriented programming (oops) oops concepts Asked in 1 Companies basic frequent | ||||
| Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. Frequently asked in HCL Technologies, TCS and Accenture. | ||||
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| Ans. final - constant variable, objects cannot be de-referenced, restricting method overriding, restricting class sub classing. finally - handles exception. The finally block is optional and provides a mechanism to clean up regardless of what happens within the try block. Use the finally block to close files or to release other system resources like database connections, statements etc. finalize() - method helps in garbage collection. A method that is invoked before an object is discarded by the garbage collector, allowing it to clean up its state. | ||||
 Sample Code for final Sample Code for finally Sample Code for finalize | ||||
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| Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application 1. Controller receives the requests and handles overall control of the request 2. Model holds majority of the Business logic, and 3. View comprise of the view objects and GUI component | ||||
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| 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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| 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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| Discuss Correct / Improve collections java data structures arraylist linkedlist arraylist vs linkedlist Asked in 61 Companies Basic frequent | ||||
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| Frequently asked to fresh graduates and less experienced developers. Among the first few questions in many interviews. | ||||
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| Ans. Composition - has-a relationship between objects. Inheritance - is-a relationship between classes. Composition - Composing object holds a reference to composed objects and hence relationship is loosely bound. Inheritance - Derived object carries the base class definition in itself and hence its tightly bound. Composition - Used in Dependency Injection Inheritance - Used in Runtime Polymorphism Composition - Single class objects can be composed within multiple classes. Inheritance - Single class can only inherit 1 Class. Composition - Its the relationship between objects. Inheritance - Its the relationship between classes. | ||||
| Sample Code for inheritance Sample Code for composition | ||||
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| Discuss Correct / Improve java java concepts inheritance object oriented programming (oops) oops concepts composition object oriented programming (oops) oops concepts inheritance object oriented programming (oops) inheritance vs composition object oriented programming (oops) oops concepts Asked in 29 Companies basic frequent | ||||
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| 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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Which access specifiers can be used with top level class ?
