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Core java - Interview Questions and Answers for 'Infoview technologies' - 13 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 | ||||
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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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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 | ||||
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Ans. abstract and final | ||||
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Like Discuss Correct / Improve  java   java keywords Asked in 2 Companies basic | ||||
Frequently asked question for intermediate developers. Frequently asked in HCL Technologies and EPAM. | ||||
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Ans. Volatile is a declaration that a variable can be accessed by multiple threads and hence shouldnt be cached. | ||||
Sample Code for volatile | ||||
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Like Discuss Correct / Improve  java   oops   synchronization   volatile   java keywords Asked in 42 Companies intermediate   frequent | ||||
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Ans. Earlier any class implementing an interface was supposed to implement all methods declared in an interface. There was no place for optionally implementing all or subset of methods.Though we have abstract classes wherein we could have provided such a mechanism by declaring some methods as abstract while providing definition for some. But as Abstract classes have a body and are comparatively heavier than interfaces and interfaces associate closely to the concept of providing interfacing than abstract classes, Java might have though of providing optional implementation for default methods. This way same interface can be reused in variety of ways rather than making copies of an interface to suit different needs. | ||||
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Like Discuss Correct / Improve  java 8   java8  interface default methods  default methods Asked in 6 Companies | ||||
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Ans. No | ||||
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Like Discuss Correct / Improve  operator overloading Asked in 1 Companies basic | ||||
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Ans. Though Static methods cannot access the instance variables directly, They can access them using instance handler. | ||||
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Like Discuss Correct / Improve  static   static method   java   oop   variables Asked in 1 Companies basic   frequent | ||||
Recently asked in Infoview Technologies. | ||||
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Ans. The no argument constructor provided by Java Compiler if no constructor is specified. | ||||
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Like Discuss Correct / Improve  java   oops   constructor   default constructor Asked in 1 Companies Basic   frequent | ||||
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Must know at all levels. Among Top 10 frequently asked questions in Java. Very frequently asked to fresh graduates or less experienced professionals. | ||||
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Ans. Its a facility for code reuse and independent extension wherein a derived class inherits the properties of parent class. | ||||
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Like Discuss Correct / Improve  inheritance  object oriented programming (oops)  oops concepts  oops concepts  java concepts  code reuse  code re-use   classes  derived classes Asked in 14 Companies basic   frequent | ||||
Frequently asked to Fresh graduates. | ||||
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Ans. http://algs4.cs.princeton.edu/11model/BinarySearch.java.html | ||||
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Like Discuss Correct / Improve  binary search  search Asked in 5 Companies basic   frequent | ||||
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All these acronyms JDK,JRE,JVM etc are very frequently asked. | ||||
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Ans. JRE or Java Runtime Environment is the Java Virtual Machine on which class files are executed. It includes borwser plugins that facilitates execution of class files in browsers. JDK or Java Development Kit includes JRE , compiler and development tools. | ||||
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Like Discuss Correct / Improve  JDK  JRE  JDK vs JRE  Difference between Asked in 4 Companies basic   frequent | ||||
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Ans. Collections in java is a framework of classes that provides an abstracted data structure to store and manipulate the group of objects. Each class is unique in the way it stores , search , sort and modify the elements. | ||||
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Like Discuss Correct / Improve  collections  collection classes Asked in 1 Companies Basic   frequent | ||||
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Ans. int[] arr = {1,-1,2,-3,3,-4,4,5,6,-5,-6,-7,-8,8,9,-9}; List positiveNumbers = new ArrayList<>(); List negativeNumbers = new ArrayList<>(); for(int i = 0; i < arr.length(); i ){ if(I < 0){ negativeNumbers.add(i); } else { positiveNumbers.add(i); } } System.out.println("Positive Numbers:" + positiveNumbers); System.out.println("Negative Numbers:" + negativeNumbers); | ||||
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Like Discuss Correct / Improve  code  program  coding Asked in 1 Companies | ||||