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Interview Questions and Answers for 'MIT' - 19 question(s) found - Order By Newest | ||||
Advanced level question. Frequently asked in High end product companies. Frequently asked in Google , Cognizant and Deloitte ( Based on 2 feedback ) | ||||
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Ans. 1. String Pool - When a string is created and if it exists in the pool, the reference of the existing string will be returned instead of creating a new object. If string is not immutable, changing the string with one reference will lead to the wrong value for the other references. Example - String str1 = "String1"; String str2 = "String1"; // It doesn't create a new String and rather reuses the string literal from pool // Now both str1 and str2 pointing to same string object in pool, changing str1 will change it for str2 too 2. To Cache its Hashcode - If string is not immutable, One can change its hashcode and hence it's not fit to be cached. 3. Security - String is widely used as parameter for many java classes, e.g. network connection, opening files, etc. Making it mutable might possess threats due to interception by the other code segment. | ||||
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Like Discuss Correct / Improve  java   oops   string   string class   immutable  immutability   advanced Asked in 39 Companies expert   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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Like 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. 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. Have been asked in HCL Technologies very frequently ( based on 3 feedback ). Among first few questions in many interviews. | ||||
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Ans. Abstract classes can have both abstract methods ( method declarations ) as well as concrete methods ( inherited to the derived classes ) whereas Interfaces can only have abstract methods ( method declarations ). A class can extend single abstract class whereas it can implement multiple interfaces. | ||||
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Like Discuss Correct / Improve  java   classes   abstract class   interfaces   abstract class vs interface   abstract classes vs interfaces Asked in 82 Companies basic   frequent | ||||
Frequently asked in all types of companies especially Indian Services companies. Frequently asked in CTS (Based on 2 feedback) | ||||
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Ans. Hashcode is used for bucketing in Hash implementations like HashMap, HashTable, HashSet etc. The value received from hashcode() is used as bucket number for storing elements. This bucket number is the address of the element inside the set/map. when you do contains() then it will take the hashcode of the element, then look for the bucket where hashcode points to and if more than 1 element is found in the same bucket (multiple objects can have the same hashcode) then it uses the equals() method to evaluate if object are equal, and then decide if contain() is true or false, or decide if element could be added in the set or not. | ||||
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Like Discuss Correct / Improve  java   collections   hashcode   advanced  hashtable Asked in 33 Companies intermediate   frequent | ||||
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Very Frequently asked to fresh graduates and less experienced. Favorite question in Walk in drives. Frequently asked in Indian Services companies. | ||||
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Ans. Overloading - Similar Signature but different definition , like function overloading. Overriding - Overriding the Definition of base class in the derived class. | ||||
Sample Code for overloading Sample Code for overriding | ||||
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Like Discuss Correct / Improve  java   oops   overloading   overriding   oops concepts   basic interview question   overloading vs overriding Asked in 86 Companies basic   frequent | ||||
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Almost sure to be asked in every company using any Dependency Injection framework ( Spring, Guice etc ) | ||||
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Ans. It is a Design Pattern that facilitates loose coupling by sending the dependency information ( object references of dependent object ) while building the state of the object. Objects are designed in a manner where they receive instances of the objects from other pieces of code, instead of constructing them internally and hence provide better flexibility. | ||||
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Like Discuss Correct / Improve  design patterns   ioc ( Inversion of Control )  dependency injection Asked in 83 Companies intermediate   frequent | ||||
Very frequently asked.Usually among first few questions. | ||||
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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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Like Discuss Correct / Improve  j2ee   mvc   mvc design pattern   design pattern   struts   spring   web application   web frameworks   ebay Asked in 60 Companies basic   frequent | ||||
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Ans. There are 2 reasons for it. 1. Usage of Primitive types - Though Java provides classes for the primitive data types but as the usage of primitives is permissible, its considered unpure OOP's language. 2. Usage of Static members - Static members belong to the class and not objects and hence not considered fit for pure OOP's programming. | ||||
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Like Discuss Correct / Improve  oops  object oriented programming  object oriented language  primitive data types Asked in 2 Companies | ||||
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Ans. With Collection classes , we cannot use primitive types. Moreover for any class using generic types, we cannot use primitive types. They add more functionality by means of additional methods. As their reference can be null , they offer consistent check for uninitialized state. They facilitate caching and reuse by means of constant Pools. | ||||
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Like Discuss Correct / Improve  wrapper classes  benefits of wrapper classes over primitives | ||||
Usually asked to entry level software developers. | ||||
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Ans. public static void main(String[] args) { int num1 = 1; int num2 = 2; num1 = num1^num2; num2 = num1^num2; num1 = num1^num2; System.out.print("num1 = " + num1 +", num2 = "+num2); } | ||||
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Like Discuss Correct / Improve  code  coding Asked in 37 Companies basic   frequent | ||||
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Ans. A wrapper class is any class which "wraps" or "encapsulates" the functionality of another class or component. A Wrapper Class that wraps or encapsulates the primitive data type is called Primitive Wrapper Class. | ||||
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Like Discuss Correct / Improve  java   wrapper classes   primitive wrapper classes | ||||
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Ans. public class BuggyBread { public static void main(String args[]) { System.out.println(factorial(5)); } private static int factorial(int number){ if(number == 1){ return 1; } else { return number * factorial(number - 1); } } } | ||||
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Like Discuss Correct / Improve  recursion Asked in 25 Companies | ||||
Frequently asked in face to face interviews. | ||||
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Ans. int count = 15; int[] fibonacci = new int[count]; fibonacci[0] = 0; fibonacci[1] = 1; for(int x=2; x < count; x++){ fibonacci[x] = fibonacci[x-1] + fibonacci[x-2]; } for(int x=0; x< count; x++){ System.out.print(fibonacci[x] + " "); } | ||||
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Like Discuss Correct / Improve  ebay   fibonacci series Asked in 66 Companies basic   frequent | ||||
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Ans. When a DML is executed, the changes only stays in session and still not pushed to DB Tables, Commit is used to push those changes to the Tables. In case we realize that we don't want to commit those changes and would like to ignore them, we can use rollback. For example - You may like that for a banking transaction you would like to update the account balance only if the debit or credit record was correctly inserted, so you may like to encapsulate both DML's - insert for transaction and update for balance in a single transaction and would only commit if both succeeds else rollback. | ||||
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Like Discuss Correct / Improve  databases  commit  rollback Asked in 2 Companies Basic | ||||
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Ans. boolean byte char double float int long short void | ||||
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Like Discuss Correct / Improve  data types  primitive data types Asked in 1 Companies Basic | ||||
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Ans. Git commit commit the changes to local repository whereas Push commits the changes to Remote repository. | ||||
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Like Discuss Correct / Improve  GIT  Configuration Management  commit vs push | ||||
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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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Like Discuss Correct / Improve  subscribe vs emit | ||||