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Q31. What is Associativity while evaluating a Java statement ?

Ans. Associativity determines whether an expression is evaluated left-right or right-left. When an expression has two operators with the same precedence, the expression is evaluated according to its associativity.

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Q32. Is New Keyword a method Name ?

Core Java

Ans. No, Its an Operator.

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Rarely asked as it was introduced with Java 8.

Q33. What is the use of :: operator wef from Java 8 ?

Core Java

Ans. We can refer to a function using this operator like System.out.println(intList.stream().reduce(Math::max).get());

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Q34. What is the difference between = and == in Java ?

Core Java

Ans. = is the assignment operator that assigns the result of the expression on the right to the variable on the left, whereas

== is the operator to check object equality to see if the reference on left and right are pointing to the same object. For primitive types, its used to check if both variables holds the same value.

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Q35. How is == operator different for objects and primitive types ?

Core Java

Ans. For objects or references, == operator check if the reference on left and right points to the same object.

For primitive types or variables, == operator check if the variable on left and right holds the same value.

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Q36. Explain what happens when insertion is performed in case of ArrayList and LinkedList.

Data Structure

Ans. Array List works on Array and when we add an element in middle of the list, Array List need to update the index of all subsequent elements. I the capacity is full, it even may need to move the whole list to a new memory location . Linked List works on Double linked list algorithm and all it has to do is to adjust the address of the previous and next elements.

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Q37. How Spliterator in Java 8 different than iterator ?

Core Java

Ans. Though there are many differences the way internally they both iterates the collections and streams respectively, but the main difference in performance that is achieved by spliterator as it can iterate Streams in Parallel whereas iterator only iterates collections sequentially.

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Q38. Which is better in terms of performance - Iterator or Spliterator ?

Core Java

Ans. Spliterator has better performance potential than iterators but only if the potential is used. Spliterator can iterate streams in parallel as well as in sequence whereas iterator can only iterate in sequence.

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Q39. Difference between Array and ArrayList ?

Core Java

Ans. <a href="http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html" rel="nofollow">http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html</a>

Sample Code for ArrayList

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Q40. Which operators in Java have highest precedence ?

Core Java

Ans. Braces, i.e () and [] have the highest precedence

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Q41. Is there a way to know size of an object in Java ?

Core Java

Ans. No, Java doesn't have a sizeOf operator. In C / C++ , its required to determine how much memory allocation is required which is not the case with Java. Java handles memory allocation and deallocation intrinsically.

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Q42. What are the cursors available in Java ?

Core Java

Ans. Enumeration
Iterator
List iterator

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Q43. Explain dot(.) operator ?

Core Java

Ans. Its used to access the object properties using the object reference or class properties using the Class Name. Moreover its used to access the classes and Interfaces of a package.

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Q44. What are the different operators in Java ?

Core Java

Ans. && - AND
|| - OR
! - LOGICAL NOT

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Q45. What is the difference between && and & in Java ?

Core Java

Ans. && is a Logical whereas & is a bitwise operator

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Q46. What are the core OOPs concepts ?

Core Java

Ans. Abstraction, Encapsulation, Polymorphism , Composition and Inheritance

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Q47. Where do you see yourself in next 5 years?

General

Ans. Sample Answers -

Getting better with upcoming technologies and be a Lead developer.

In accordance with the company, working as a permenant employee.

Be an associate architect.

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Q48. What is the precedence of operators in Java ?

Core Java

Ans. http://introcs.cs.princeton.edu/java/11precedence/

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Q49. What is a mutator in Java?

Core Java

Ans. Mutator is another name for setter methods, i.e the method allows for mutating the property of an object and eventually the state of the object.

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Q50. Why do we need Garbage collection ?

Core Java

Ans. Garbage collection mechanism frees up the memory that is no longer needed. In languages like C / C++ the deallocation needs to be done explicitly by the programmer and hence any leniency may result in memory leak. Garbage collection in java ensures that all unused memory is reclaimed and hence there are no memory leaks.Moreover it relieves the programmer from the hassle of carefully releasing all memory.

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Q51. Explain OOPS.

Core Java

^{This question was recently asked at 'Acute Informatics,General Atomics'.This question is still unanswered. Can you please provide an answer.}

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Q52. What is the difference between Enumeration and Iterator ?

Core Java

Ans. Enumeration can iterate only legacy collections like Vector , HashTable and Stack whereas Iterator can iterate both legacy and non legacy collections.

Enumeration is less safer than Iterator

Enumeration is fail safe whereas Iterator is fail fast

Iterator allows for removal of element while traversal whereas Enumeration doesn't have remove method.

Enumerations were introduced in Java 1 whereas Iterators were introduced with Java 2

Enumerations have methods like hasMoreElements and nextElement whereas Iterators have methods like hasNext, next and remove

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Q53. Which of the following is valid greater than and equal to operator in Java ?

>=
=>

Core Java

Ans. >=

=> will result in error.

=> somewhat looks like lambda operator "->"

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Q54. What is a ternary operator ?

Database

Ans. Ternary operator , also called conditional operator is used to decide which value to assign to a variable based on a Boolean value evaluation. It is used as

condition ? value1 : value2

For example

int y = (x > 0) ? x:0; // assign x if it's greater than 0, else assign 0

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Q55. Why doesn't java support operator overloading ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

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Q56. How can i split a linked list in two parts in java 8?

Core Java

Ans. This can be done using a Spliterator.

LinkedList list = Arrays.asList("names","numbs","birds","animals");
Spliterator split1 = list.Spliterator();
Spliterator split2 = split1.Spliterator();

Now, the LinkedList is split into split1 and split2.
use split2 first then split1 to check the output.

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Q57. 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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Q58. Can we modify a list while iterating it ?

Core Java

Ans. No,we cannot.I t will give concurrentModificationExceptin error. It can be resolved by using ConcurrentClasses like ConcurrentHashMap,CopyOnWriteArrayList,BlockingQueue etc which are fail-safe and wont give exception.

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Q59. Design ATM machine application using oops.

Design

^{This question was recently asked at 'Atos'.This question is still unanswered. Can you please provide an answer.}

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Q60. What is garbage collection ?

Core Java

Ans. The garbage collection is a facility wherein a program runs on the Java Virtual Machine which gets rid of objects, which are not being used by a Java application anymore. It is a form of automatic memory management and recollection.

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