Question 1

Which of the following is not the other name of attriibute?

Accepted Answer

Instance is an object not an attribute

Question 2

In a single virtual machine, the Java programming language passes arguments by

Accepted Answer

In single virtual machine,JVM passes arguments only by value.

Question 3

Which key word is to be used to tell the JVM to skip the variable while performing the serialization process of the object containing it?

Accepted Answer

If you mark an instance variable as transient, you're telling the JVM to skip (ignore) this variable when you attempt to serialize the object containing it.

Question 4

Which method names follow the JavaBeans standard?

Accepted Answer

C use the valid prefixes 'get' and 'is

Question 5

What is the difference between throw and throws clause?

Accepted Answer

A throw is used to throw an exception manually, where as throws is used in the case of checked exceptions, to tell the compiler that we haven't handled the exception, so that the exception will be handled by the calling function

Question 6

What are the various elements of OOPS?

Accepted Answer

Various elements of OOP are: • Object • Class • Method • Encapsulation • Information Hiding • Inheritance • Polymorphism

Question 7

A lock can be acquired on a class. The above statement is

Accepted Answer

A lock can be acquired on a class. This lock is acquired on the class's Class object.

Question 8

Which of the following modifiers can be used with Local inner class?

Accepted Answer

It can either be Final or Abstract

Question 9

How many types of classes are there in Java?

Accepted Answer

Two types of classes: 1) Top Level Class 2) Classes within Class i) member classes a) static member class b) non static member class ii) local classes iii) anonymous classes

Question 10

If you are using C language to implement the heterogeneous linked list, what pointer type will you use?

Accepted Answer

The heterogeneous linked list contains different data types in its nodes and we need a link, pointer to connect them It is not possible to use ordinary pointers for this So we go for void pointer Void pointer is capable of storing pointer to any type as it is a generic pointer type

Question 11

What is Overloading Polymorphism?

Accepted Answer

Overloading allows multiple functions to exist with same name but different parameters Again if you take bike as an example, it has a function Start with two forms ie ’Auto Start’ and ’kick start’

Question 12

In RDBMS, what is the efficient data structure used in the internal storage representation?

Accepted Answer

B+ tree. Because in B+ tree, all the data is stored only in leaf nodes, that makes searching easier. This corresponds to the records that shall be stored in leaf nodes

Question 13

What is JAR file?

Accepted Answer

A JAR file (short for Java Archive) is a ZIP file used to distribute a set of Java classes It is used to store compiled Java classes and associated metadata that can constitute a program

Question 14

What is polymorphism?

Accepted Answer

It is the ability of an object to behave differently on different situations for the same message

Question 15

When do you use :: Operator in C++?

Accepted Answer

:: is the scope resolution operator When local variable and global variable are having same name, local variable gets the priority C++ allows flexibility of accessing both the variables through a scope resolution operator

Question 16

Explain Overriding Polymorphism.?

Accepted Answer

Overriding means changing behavior of methods of base class in derive class by overriding the base class methods If class A is a base class with method ’calculate’ and class B inherits class A, thus derives method ’calculate’ of class A The behavior of ’calculate’ in class B can be changed by overriding it

Question 17

When should I use abstract classes and when should I use interfaces?

Accepted Answer

Use Interfaces when… - You see that something in your design will change frequently - If various implementations only share method signatures then it is better to use Interfaces - You need some classes to use some methods which you don't want to be included in the class, then you go for the interface, which makes it easy to just implement and make use of the methods defined in the interface Use Abstract Class when… - If various implementations are of the same kind and use common behavior or status then abstract class is better to use - When you want to provide a generalized form of abstraction and leave the implementation task with the inheriting subclass - Abstract classes are an excellent way to create planned inheritance hierarchies They're also a good choice for nonleaf classes in class hierarchies

Question 18

How do you traverse through a collection using its Iterator?

Accepted Answer

To use an iterator to traverse through the contents of a collection, follow these steps: - Obtain an iterator to the start of the collection by calling the collections iterator() method - Set up a loop that makes a call to hasNext() Have the loop iterate as long as hasNext() returns true - Within the loop, obtain each element by calling next()

Question 19

How do you decide when to use ArrayList and When to use LinkedList?

Accepted Answer

If you need to support random access, without inserting or removing elements from any place other than the end, then ArrayList offers the optimal collection If, however, you need to frequently add and remove elements from the middle of the list and only access the list elements sequentially, then LinkedList offers the better implementation

Question 20

What is the Set interface ?

Accepted Answer

- The Set interface provides methods for accessing the elements of a finite mathematical set - Sets do not allow duplicate elements - Contains no methods other than those inherited from Collection - It adds the restriction that duplicate elements are prohibited - Two Set objects are equal if they contain the same elements

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