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Accenture First & Second Round: Technical Interview Questions

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Accenture First & Second Round: Technical Interview Questions

Java Interview questions:

1) Why is Java called platform independent?

Java is platform independent that means we can execute our code in any operating system either it is mac, Window or Linux. Java is Platform independent because when we write code, then its compiler converts it into bytecode and this bytecode can be executed on any platform (JDK should be installed in that OS).

2) What do you understand by Exception Handling?

Exception handling is a process of handling exceptions occurs during the execution of a program. Due to the occurrence of exception, execution of programs get halted, so it is very important to handle these exceptions so that program can be executed smoothly. We can handle the exceptions by using five keywords: try, catch, throw, throws, and finally.

3) What is checked and unchecked exception?

Checked exception: If the exception occurs or checked at compile time during the execution of a program, it is called as the checked exception. We should handle these exceptions using try-catch block or using throws keyword.
E.g., if someone tries to read a file which is not present then it will throw a checked exception at compile time FileNotFoundException
Unchecked exceptions: If the exception is not checked at compile time and occurred at runtime then this type of exception is called an unchecked exception. This type of exceptions occur due to an error in the logic of the code. If we do not handle this type of exception then also compiler will not give a compilation error.
E.g. ArithmeticException

4) What are the reasons behind the occurrence of an exception?

Following are the reasons behind the occurrence of an exception:

Accessing a file, which does not exist
Dividing a variable by zero
Inserting an element in the array outside the range
If throw statement occurs
Abnormal execution condition captured by JVM

5) What is OOP concept?

OOP stands for Object-Oriented Programming. Object-Oriented Programming is a coding practice which works with objects and class. Java is one of the programming languages which is based on these concepts. The basic OOP concepts are:

Object
Class
Inheritance
Polymorphism
Abstraction
Encapsulation

6) Explain the basic features of OOPs.

Following are the basic features of OOPs:

Object: – An object is a physical entity which has a state and behaviour. It occupies space in memory. It is a sample of a class. Object helps to access the methods and variables in the program.
Class – A Class is “collection of objects.” A class is a logical entity, which does not take any space. A class includes all the data and methods which shows the behaviour of an object.
Inheritance – Inheritance is a process by which one class can have all properties of other class. Inheritance increases the code reusability. There are two terms used
- Child class (Subclass): Class which inherits other class, called as Child class or derived class.
- Parent class (Superclass): A class which got inherited by another class is termed as parent class or Base class.
Polymorphism: – Polymorphism is a method of performing “a single task in different ways.” Polymorphism enables a programmer to use methods or operators in different ways. In Java, we use method overloading and overriding to obtain the polymorphism.
Abstraction: If we show only functionality and hide the explanations or details then this process is called as Abstraction. For achieving the abstraction, we use two ways in Java
- Abstract class
- Interface
Encapsulation: Encapsulation is a process of enclosing the data and code together to form a single unit. It makes the data safer within the code for any modification. For achieving the encapsulation, we can declare the data variables of class as private.

7) Differentiate between class and object.

The class and object both are the features of OOPs concepts. The basic differences between both features are given below:

The Class is a logical entity whereas Object is a physical quantity.
Class does not occupy memory at the time of creation whereas Object occupied space in memory when it is created.
For declaring a class, we use a ‘class’ keyword followed by a class name, whereas we can create the object using the ‘new’ keyword in Java.
A Class is like a factory which generates object and object are the instances of the class.

8) What is encapsulation in Java?

Encapsulation is a process of enclosing the data and code together to form a single unit. The best example to understand the encapsulation is a capsule which contains the medicine in it.

If we declare all the data members of the class as private, then it is called a fully encapsulated class in Java, and then we can use getter and setter method to access it.
One of the examples of the fully encapsulated class is Java Bean class.
Encapsulation keeps its data hide from other class hence it is also called as data-hiding.

Example for encapsulation:

class EncapsulationEg{
    private String empname;
    private int empage;
    private int empid;
    public String getEmpName() //getter method 
    {
        return empname;
    }
    public int getEmpAge()
    {
        return empage;
    }
    public int getEmpId()
    {
        return empid;
    }
    public void setEmpName(String setvalue)  //setter methods 
{
        empname=setvalue;
    }
    public void setEmpAge(int setvalue){
        empage=setvalue;
    }
    public void setEmpId(int setvalue){
        empid=setvalue;
    }
    }
    public class TestEncapsulation{
        public static void main(String args[]){
         EncapsulationEg en= new  EncapsulationEg();
         en.setEmpName(“Alvin”);
        en.setEmpAge(22);
        en.setEmpId(12568);
         System.out.println(“Employee Name: “ +en.getEmpAge());
         System.out.println(“Employee Age: “ +en.getEmpAge());
         System.out.println(“Employee ID: “ +en.getEmpId());
    }
}

Output:

Employee Name: 22
	Employee Age: 22
	Employee ID: 12568

9) What is Recursion and recursive function in Java?

Recursion is a process of calling a method by itself continuously till not get termination point. A method which calls itself is called as a recursive method.

Syntax:

Return-type method_name()
{
// Code to be executed
method_name(); // same name of calling method   }

10) How can you differentiate between C, C++, and Java?

There are the following differences between the C, C++, and Java language.

Index	C language	C++	Java
1.	C language is a procedural language.	C++ is an object-oriented language.	Java is also an object-oriented language (not pure as it also supports primitive data types).
1.	C language is platform dependent.	C++ is platform dependent.	Java is platform independent language.
1.	C language supports pointers.	C++ language also supports pointers.	Java does not support pointers.
1.	We cannot create our own package in C language	In C++ language also, we cannot create our package.	In the Java language, we can create our package and can specify the classes.
1.	In C, there is no any concept of inheritance.	In C++, we can use multiple inheritance.	Java does not support multiple inheritance.

11) What do you understand by runtime polymorphism?

Polymorphism is a method of performing “a single task in different ways.” Polymorphism is of two types

Runtime Polymorphism
Compile-time polymorphism

Here we will discuss runtime polymorphism.

Runtime Polymorphism– We can achieve runtime Polymorphism by method overriding in Java. And method overriding is a process of overriding a method in the subclass which is having the same signature as that of in superclass.

class A{    //Superclass
void name()
{
System.out.println(“this is student of Superclass”);
}
}
class Student extends A  //Subclass
{
void name(){      // method Override with same signature(runtime polymorphism)
System.out.println(“this is student of subclass”);
}
public static void main (String[] args) {
A a= new A();    // refrence of A class
A b= new Student();   // refrence of student class
a.name();
b.name();
}
}

Output:

this is student of Superclass
this is student of subclass

12) How can you differentiate between method overloading and method overriding?

No.	Method overloading	Method overriding
1.	The process of calling two methods having the same name with different parameters is called method overloading (in the same class)	The process of calling two methods, one in the subclass and other in the superclass, having the same signature is called as method overriding.
2.	It can be accessed within a class.	Method overriding requires two classes to be accessed which having IS-A relationship.
3.	Return type may be changed or may remain same with different parameters	Return type should be the same for both methods.
4.	Method overloading is a concept of compile-time polymorphism.	Method overriding is a concept of method overriding.
5.	e.g. class A{ void m1() {// codes…….} Void m1 (int a) {//code………}	e.g. class A { void m1(){ // code…………} } Class B extends A{ Void m1(){ // code………..}

13) What are the keyword “super” and “this” in Java?

super keyword: “super” is a keyword in Java which is used to give reference to the object of parent class. “super” keyword cannot be used as an identifier as it is reserved keyword in Java.

this Keyword: “this” keyword in Java is used to refer to the object of the current class. The ‘this’ keyword cannot be used as an identifier as it is a reserved keyword in Java.

14) What is an interface in Java? Can we implement multiple interfaces in one class?

Interface in Java is a way to achieve the abstraction. The Interface is like a class but not exactly as Interface also can have methods and variable as the class does but Interface only contain method signature does not have the body.

The Interface cannot be instantiated in Java.
The Interface contains methods which are public and abstract (by default).
A class can implement an interface.
For declaring an interface, we use the keyword interface.

Syntax:

interface Interface_Name{
//Methods
}

We can implement multiple interfaces in one class and parent interfaces can be declared using a comma(,) operator.

Syntax:

public class A implements C, D {
Code
}

15) Explain inheritance in Java? How can it be achieved?

Inheritance in Java is a process by which one class can have all properties of other class. That means one class inherits all the behaviour of the other class.
Inheritance increases the code reusability.
Inheritance is an important feature of OOP concept.
Inheritance is also a representation of the IS-A relationship

There are two terms used in inheritance:

Child class (Subclass): Class which inherits other class, called a Child class or derived class.
Parent class (Superclass): A class which got inherited by another class is termed as parent class or Base class.

The Syntax of java inheritance:

Class A extends B     // Here A represents subclass and B represent Superclass
{
// Code 
}

16) Can we use multiple inheritance in Java? Explain with reason?

No, we cannot use multiple inheritance in java as it creates ambiguity and diamond problem in the program. To overcome this problem, we can use interface in Java.

Let suppose class A inherits the two parent class B and C in which a method with the same name is present in both the classes and hence when we try to override that method it will create confusion for the compiler and will give the compilation error. Therefore, Java doesn?t support multiple inheritance.

17) What can we do if we want to access a private member of a class?

We can access private members of the class by using public getters and setters from outside the class in Java.

18) What is the significance of “static” keyword?

Static keyword in Java is a non-access modifier which can be used with the block, variable, methods, and nested classes.
Static Keywords are the part of the class, and it does not belong to the instance of the class.
We use static keyword in java with variables, block, and method for achieving memory management.
Java static property can be shared by all the objects.
For accessing the static members, we don’t need to create the instance of the class.

19) What is “Collection Framework” in Java?

Collection Framework in Java is an architecture for storing the classes, and interfaces and manipulating the data in the form of objects. There are two main interfaces in Collection Framework that are:

Java.util.Collection
Java.util.Map

20) What is List interface in collections?

List interface is an interface in Java Collection Framework. List interface extends the Collection interface.

It is an ordered collection of objects.
It contains duplicate elements.
It also allows random access of elements.

Syntax:

public interface List<E> extends Collection<E>

21) What do you understand by object cloning?

Object cloning is a mechanism of creating the same copy of an object. For object cloning, we can use clone() method of the Object class. The class must implement the java.lang.Clonable interface, whose clone we want to create otherwise it will throw an exception.

Syntax of clone() method:

protected Object clone() throws CloneNotSupportedException

22) Can we insert duplicate values in Set?

We cannot insert duplicate elements in Set. If we add a duplicate element, then the output will only show the unique elements.

23) What is the difference between Collections, and Collection in Java?

Collection and collections both are the part of Java Collection Framework, but the primary differences between both are given below:

A Collection is an interface in java and Collections is a class of collection framework.
The Collection interface provides the methods that can be used for data structure whereas Collections class provides the static methods which can be used for various operation on a collection.

24) What is “Diamond problem” in Java? How can it be removed?

The Diamond problem occurs in multiple inheritance, but Java does not allow multiple inheritance. In case of Java, it can occur with interfaces. When we implement two interfaces which are having methods with the same signature then it creates ambiguity for the compiler, and it gives compile time error. Its structure looks like diamond so it is called as Diamond problem.

E.g. Let’s take an example which will show the diamond problem.

interface InterfaceA {
default public void m1() { System.out.println(“This is interface A!”); }
}
interface InterfaceB {
default public void m1(){ System.out.println(“This is interface B!”); }  //same signature as interface InterfaceA?
}
public class Simple implements InterfaceA, InterfaceB {
public static void main(String args[]) {
Simple s1= new Simple();
s1.m1();   // It will give error..
}}

Error: Simple.java:10: error: class Simple inherits unrelated defaults for m1() from types InterfaceA and InterfaceB

25) What is an abstract class in Java?

An Abstract class is used to achieve abstraction in Java. If we use the keyword “abstract” with the class name, then it is called as an abstract class.
An Abstract class can have only methods without body or can have methods with some implementation.
The Abstract class cannot be instantiated
It’s not necessary that an abstract class should have an abstract method.

Syntax:

abstract class Student{
}

26) What is deadlock condition in multithreading?

A Deadlock condition occurs in the case of multithreading. It is a condition when one thread is waiting for an object lock, which is already acquired by another thread and the second thread is waiting for lock object which is taken by the first thread, so this is called deadlock condition in Java.

27) Differentiate between Collection and array.

The Collection and Array both are responsible for storing the data, but the fundamental differences between both are given below:

Arrays are always of fixed size, we cannot change its size at runtime, but In Collection, size can be changed dynamically.
Arrays can only store homogeneous or similar type objects, but in Collection, both homogeneous and heterogeneous objects can be stored.
Arrays cannot provide the “ready-made” methods for user requirements as sorting, searching, etc. but Collection includes readymade methods to use.
Arrays are good in performance as compare to Collection but Array take more space in memory in comparison to Collection.

C/C++ Interview Questions

28) What is call by value and call by reference?

There are two ways in C language to pass the values in the function that are:

Call by Value
Call by reference

Call by value: In call by value, a copy of the value is passed to the function so, if we change in formal parameters it will not affect the actual parameters. When we change in the value of the formal parameter in the “calling function,” it just takes it as the local variable and does not affect the actual value.

Call by reference: In call by reference, an address of that value is passed to the function so, if we make any changes in formal parameters it will affect the actual parameter as well.

29) Explain dynamic memory and static memory allocation.

There are two types of allocation of memory:

Static memory allocation: The allocation of memory at the starting of the program is called static memory allocation. In static memory allocation size remains fix i.e. we cannot change the size at runtime. Static memory allocation is used in Array.
Dynamic memory allocation: The allocation of memory at runtime is called as dynamic memory allocation. We can specify a size at runtime as per need. The memory gets allocated from heap area, and it can also be deallocated from same. Dynamic memory allocation used in pointers.

30) What is difference between “var++” and “++var”?

The expressions, ( var++)and ( ++var) both are used for the incrementing the value of variable var.

The main difference between both is that, (var++ ) it gives the evaluation of statement first and then it increments the value by one whereas (++var) is used as it increments the value by one before the evaluation of the expression.

E.g.

#include <stdio.h>
int main()
{
int a,b;
a=5, b=1;
printf(“%d %d”, a++, a);   //will generate 5, 6 as output
printf(“%d %d”, ++b, b);    //will generate 2, 2 as output
)

31) Differentiate between class and structure in C++.

The class and structure both are approximately equivalent to each other. But the main differences between both the terms are given below.

The members of the class are accessed as private by default whereas members of the structure are accessed public by default.
Class in C++ is a group of objects, related variables, and functions, whereas Structure is a user-defined data type which performs its operation
We can declare a class using the keyword ‘class’, whereas we can declare a structure using the keyword ‘struct.’
The objects of the class, created at heap area of the memory, whereas the object of the structure created on stack area of memory.

32) What are the access specifiers in C++?

We use access specifier to prevent the access of the class members or to implement the feature of Data Hiding. In C++, there are some keywords used to access specifier within class body, which are given below:

Public: If we specify a class member as public then it will be accessible from anywhere within a program. We can directly access the private member of one class from another class.
Private: If we specify any class member as private then it will only be accessed by the function of that class only. We cannot access the private member of the class outside the class.
Protected: Protected access specifier is mainly used in case of inheritance. If we define the class member as protected, then we cannot access class member outside the class, but we can access it by subclass or derived class of that class.

E.g. Below is the example to show the access specifier in C++.

33) Why we use of “getch()” in a program?

The getch() function is a predefined library function which is used to take a input character from the screen, and it holds the screen till it not get character from input.

#include<stdio.h>
main()
{
printf(“enter the character. \n”);
getch();
}

Output:

enter the character.

34) What does “main()” function in C++? Can we run a program without main method?

In C++ programming language the main() function is the entry point of that program. When we start execution of any program, execution directly goes to the main() in the program.

Syntax for main():

void main(){
///Program body;
}

35) What is the declaration and definition of a variable?

Declaration of Variable: Declaring a variable or function is that we are declaring the name and its type so that it can be used in the program. The Compiler can understand and use those variables and functions. Declaring a member gives its representation in that program.

e.g.

extern int x;
extern char  y;     // It tells the compiler that there are two variables x and y of types char and int

Definition of Variable: Defining a variable means, we are providing some value to it, or we are initializing it with some value. Defining a variable or any member of the program gives the complete information about it.

e.g.

int x= 2;
char y = ‘A’,  ‘B’;    // It defines the variable  x and y by giving its value or body.

36) What do you understand by Friend function?

A friend() function in C++ is a function which can access private and protected members of another class in which it is declared as a friend. We can declare a function as a friend function by using keyword friend. A friend function can be of two types:

Method of another class
A global function

Syntax:

class Class_Name {
//Line of code
friend return-type func_name() ;}

The above-declared friend function can use private members of the class.

37) What is memory allocation in C?

Memory allocation is a process of allocating or reserving some portion of the memory (or as per need) for the execution of the code.

There are mainly two types of memory allocation in C:

Static memory allocation
Dynamic memory allocation

Static memory allocation: The allocation of memory at the starting of the program is called static memory allocation. In static memory allocation size remains fix, i.e., we cannot change the size at runtime. Static memory allocation is used in Array.
Dynamic memory allocation: The allocation of memory at runtime is called as dynamic memory allocation. We can specify a size at runtime as per need. The memory gets allocated from heap area, and it can also be deallocated from same. Dynamic memory allocation used in pointers. There are four types of the predefined function used for dynamic memory allocation
1. malloc()
2. calloc()
3. free()
4. realloc()

38) Differentiate between malloc() and calloc()?

The malloc() and calloc() are the two pre-defined library function available in <stdlib.h> Library. Both the functions are used for dynamic memory allocation for the execution of the program. The basic differences between the malloc() and calloc() are given below:

The malloc() stands for memory allocation while calloc() stands for contiguous allocation
The malloc() allocates a single block of memory whereas calloc() allocates multiple blocks of memory.
The malloc() takes only one argument, i.e., size of given block. Whereas calloc() takes two arguments, i.e., a number of blocks to be allocated and size of all blocks.
The malloc() function is faster than calloc() function for memory allocation.

Syntax for malloc() function:

ptr= (type_cast*) malloc( size_t size );

Syntax for calloc() function:

ptr= (type_cast *) calloc(n , size_t size );

39) Why is C a procedural language?

Procedural language defines a language which follows some pattern, hence C language is called as procedural language as in C language a programmer must follow a specific pattern or flow of the program. C language follows a top-down approach to solve a problem. It mainly focuses on the flow of the program rather than the data.

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60 Wipro important Technical Interview Questions with Answers

by Team IM | Jan 25, 2022 | Any Branch, Any Degree, Bangalore, Batch 2017, Batch 2018, Batch 2019, Batch 2020, Batch 2021, Batch 2022, BCA Job, Blog, Branch CIVIL, Branch CSE, Branch ECE, Branch EEE, Branch EN, Branch IT, Branch ME, BTech Job, Companies Recruitment Notifications, Govt. Jobs, Govt. Jobs Notifications, Internships, Interview Preparation, IT Jobs, MCA Job, Miscellaneous, Pune, Technical, Wipro

Wipro Technical Interview Questions

1) What are the functionalities of an operating system?

These are some major functionalities of an operating system:

The operating system shares the Computer’s memory and sharing of the central processing unit time by various applications and peripheral devices.
An operating system provides a user interface, i.e., graphical user interface and command line.
An operating system includes functionality for booting the computer.
Perform some basic tasks, i.e., managing the peripheral devices.
It provides file management which refers to the way that operating system stores, retrieves, manipulates, and saves data.

2) What is the difference between UNIQUE key and PRIMARY key constraints?

Difference between unique key and primary key constraints:

Unique key	Primary key
A table can contain multiple unique keys.	A table can contain only one primary key.
NULL values are allowed.	NULL values are not allowed.
It helps to maintain a unique data in a column of a table.	It helps to identify a unique row from a table.
For MS SQL server databases, a unique constraint will generate a unique NON-CLUSTERED INDEX	Primary key will generate a unique CLUSTERED INDEX

3) How can you delete the duplicate row in a table?

In case of duplicate rows, you have to be more careful at the time of fetching records from the table.

To overcome this problem, we use a DISTINCT keyword.

It is used along with a SELECT statement to eliminate all duplicate records and fetching unique records.

Syntax:

The basic syntax to eliminate duplicate records from a table is:

SELECT DISTINCT column1, column2,….columnN
FROM table _name
WHERE [conditions]

4) Define the SQL Profiler?

SQL Profiler can be defined as the profiler utility which is mainly used to track connections to the SQL Server and also determine the activities such as which SQL Scripts are running, and which one is getting failed, etc.

5) What is stored procedure? Explain with example.

Stored procedures are a batch of SQL statements that can be executed in a couple of ways. Most of the DBMS support stored procedures; however, not all do. The stored procedure increases the reusability as here the code or the procedure is stored into the system and used again and again that makes the work easy.

Syntax:

CREATE PROCEDURE procedure_name
AS
sql_statement
GO;

To execute a stored procedure

EXEC procedure_name;

Create a table and use this syntax for example.

6) What is a process and what is a thread?

A thread is a lightweight sub-process, the smallest unit of processing. It is a separate path of execution.

Threads are independent that means if there is an exception in one thread, it doesn’t affect other threads. It uses a shared memory area.

The process is heavyweight and can consists of multiple threads. It is a small part of a program.

7) What are the advantages of a thread? How does the multithreading look like?

These are the following advantages of a Thread:

It provides efficient communication.
It minimizes the context switching time.
By using thread, we can get the concurrency within a process.
Thread allows utilization of multiprocessor architectures to a greater scale and efficiency.
A process which executes multiple threads simultaneously is known as multithreading.
A thread is a lightweight sub-process, the smallest unit of processing.

To achieve multitasking in java, we have two ways:

Multiprocessing and multithreading

One process may contain more than one thread and execute simultaneously is known as multi-threading.

8) What are Multi-Processing and Multitasking?

Multitasking: As the name indicates multiple tasks run on a single CPU. We use multitasking to utilize the CPU.

Multitasking can be achieved in two ways:

Process-based Multitasking (Multiprocessing)
Thread-based Multitasking (Multithreading)

Multi-processing: Multi-processing refers to the ability of a system to support more than one central processing unit at the same time.

Multithreading: As the name indicates multiple threads run concurrently.

A thread is a lightweight sub-process, the smallest unit of processing.

9) What are stack and Queue and its applications?

Stack

The stack is an ordered list in which, insertion and deletion can be performed only at one end that is called a top.
The stack is a recursive data structure having a pointer to its top element.
Stacks are sometimes called as Last-In-First-Out (LIFO) lists, i.e., the element which is inserted first in the stack will be deleted last from the stack.

Applications of Stack:

Recursion
Expression evaluations and conversions
Parsing
Browsers
Editors
Tree Traversals

Queue

A queue can be defined as an ordered list which enables insert operations to be performed at one end called REAR and delete operations to be performed at another end called FRONT.
The queue is referred to be as the First-In-First-Out list.
For example, people waiting in line for a rail ticket form a queue.

Applications of Queue:

The queues are widely used as waiting lists for a single shared resource like a printer, disk, CPU.
The queues are used in the asynchronous transfer of data (where data is not being transferred at the same rate between two processes), e.g., Pipes, file IO, sockets.
The queues are used as buffers in most of the applications like MP3 media player, CD player, etc.
The queues are used to maintain the playlist in media players to add and remove the songs from the playlist.
The queues are used in operating systems for handling interrupts.

10) What is indexing, what are the advantages and disadvantages of it?

Indexes are special lookup tables. It is used to retrieve data from the database very fast.

An Index is used to speed up select queries and where clauses. But it shows down the data input with insert and update statements. Without affecting the data, we can create or drop indexes

An index in a database is just like an index in the back of a book.

Indexing can be of the following types

Primary index, secondary index, and clustering index.

The advantages of indexes are as follows:

An index makes it possible to retrieve data quickly.
Index’s use in queries usually results in much better performance.
They can be used for sorting. A post-fetch-sort operation can be eliminated.
Index guarantees uniquely identifiable records in the database.

The disadvantages of indexes are as follows:

Indexes decrease the performance on inserts, updates, and deletes.
Indexes take up space (this increase with the number of fields used and the length of the fields).
Databases will have monocase values in fields that are indexed.

11) What is De-Normalization where does it have?

Denormalization is the process of boosting up database performance and adding of redundant data which helps to get rid of complex data. Denormalization is a part of database optimization technique. This process is used to avoid the use of complex and costly joins.

Denormalization doesn’t refer to the thought of not to normalize instead of that denormalization takes place after normalization. In this process, firstly the redundancy of the data will be removed using normalization process than through denormalization process we will add redundant data as per the requirement so that we can easily avoid the costly joins.

12) What are the Different Objects in DBMS?

A database objects use to store or reference data in the database. Any statement which is written with CREATE Command is known as the database object.

Different types of object in DBMS are:

View: This object is used to create a view in the database. It is a logical table based on another view. A table on which view is based is called the base table.

Table: we can create a table in a database by using the CREATE TABLE statement.

Sequence: This object command used to create a sequence in the database. It is a user-created database object which is shared by multiple users to generate unique integers.

Index: A database object can create indexes in the database by using an index. Indexes are used for fast retrieval of rows from a table.

Synonym: This object is also used for creating indexes in the database. By synonym, you can easily access the objects

13) What are Self-Join and Outer Join, where do you use it?

Self-Join: A self-join is a join which joins the table with itself, means that each row of the table is combined with itself and with every other row of the table. The table contains a FOREIGN KEY which references its PRIMARY KEY.

It shows the one-to-many relationship in a table also known as a unary relationship.

Now come to SQL outer join, all the content of both tables is integrated together either they are matched or not.

An outer join is of two types:

1. Left outer join (also known as left join): this join returns all the rows from left table combine with the matching rows of the right table. If you get no matching in the right table, it returns NULL values.

Syntax: Left outer join

SELECT table1.column1, table2.column2…..
FROM table1
LEFTJOIN table2
ON table1.column_field = table2.column_field;

2. Right outer join (also known as right join): this join returns all the rows from right table are combined with the matching rows of left table .If you get no column matching in the left table .it returns null value.

Basic syntax for right joins:

SELECT table1.column1, table2.column2…..
FROM table1
RIGHT JOIN table2
ON table1.column_field = table2.column_field;

15) Explain some differences between TRUNCATE and DELETE commands with their syntax?

There is a slight difference b/w delete and truncate statement. The DELETE statement only removes the rows from the table based on the condition defined by WHERE clause or remove all the rows from the table when the condition is not specified.

But it does not free the space containing by the table.

16) Define memory management in C.

When you run a program, it loads into your computer memory and starts execution by sending and receiving the instructions from the computer’s processor. When your program needs to run a function, then it loads at another part of the memory till it runs and releases that memory when the task is complete.

Now, talk about the concept of dynamic memory allocation in c language, which enables the C programmer to allocate memory at runtime. Dynamic memory allocation in c language is possible by four functions of stdlib.h header file.

malloc()
calloc()
realloc()
free()

17) What are the steps involved in designing complete software?

To build software, a programmer should have to follow the SDLC.

Software development life cycle is a process of developing new software

There are six steps of SDLC:

Planning: Plan about the scope, approach, functionalities, etc.
Requirement analysis: Gather the required tools, data, and information that are required for the project
Designing: Design a prototype to check the architecture of the project.
Coding: coding as per designing.
Testing: testing is done to check whether the actual result meets the required result.
Maintenance: Updates

18) What is the difference between Abstract classes and interface?

Java interface should be implemented using the keyword “implements”; A Java abstract class should be extended using the keyword “extends.”

An Interface can extend interface only; Abstract class have two properties, it can extend only one java class but implement more than one interface at a time.

19) What is the property of a class?

We can define property in a way that property is a member of a class that provides the access of an object or a class to an attribute. For e.g., Properties include the length of a string, the size of a font, the caption of a window, the name of a customer, and so on.

20) Define precondition and postcondition to a member function.

A pre-condition is a condition that must be true before a method runs for it to work

A post-condition is a condition that must be truly guaranteed after a method is finished.

If all the preconditions of this method are satisfied, then postconditions will also meet for the same method.

No guarantee for behavior if the preconditions not meet.

21) How can you sort the elements of an array in ascending order?

C program to sort the element of an array in ascending order.

#include<stdio.h>
include<conio.h>
void main()
   {
       int i, j, a, m, num[30];
       printf(“Enter the value of N \n”);
       scanf(“%d”, &m);
       printf(“Enter the numbers \n”);
       for (i = 0; i < m; ++i)
           scanf(“%d”, &num[i]);
       for (i = 0; i < m; ++i)
       {
           for (j = i + 1; j < m; ++j)
           {
               if (num[i] > num[j])
               {
                   a =  num[i];
                   num[i] = num[j];
                   num[j] = a;
               }
           }
       }
       printf(“Ascending order of elements \n”);
       for (i = 0; i < m; ++i)
           printf(“%d\n”, num[i]);
   }

22) How can you sort the elements of an array in descending order?

C program to sort the element of an array in descending order.

#include<stdio.h>
include<conio.h>
   void main ()
   {
       int num[30];
       int i, j, a, m;
       printf(“Enter the value of N\n”);
       scanf(“%d”, &m);
       printf(“Enter the numbers \n”);
       for (i = 0; i < m; ++i)
        scanf(“%d”, &num[i]);
       /*  sorting begins … */
       for (i = 0; i < m; ++i)
       {
           for (j = i + 1; j < m; ++j)
           {
               if (num[i] < num[j])
               {
                   a = num[i];
                   num[i] = num[j];
                   num[j] = a;
               }
           }
       }
       printf(“Descending order of the elements \n”);
       for (i = 0; i < m; ++i)
       {
           printf(“%d\n”, num[i]);
       }
   }

23) How is macro execution faster than a function?

Macros can define before the main method or within the main method. Macros are pre-processed that means all the macros are processed before the compilation of the program, and the functions are processed after compilation of the program.

24) Write a program to sort the string by using bubble sort.

Bubble sort: Bubble sort is a technique by which you can print the elements of an array in ascending or descending order. Bubble sort is used to sort string too.

Program to sort the string:

 #include <stdio.h>
#include <string.h>
void main()
{
int num, i, j;
char name[15][20], temp[20];
printf(“\n Sorts the strings of an array using bubble sort :\n”);
printf(“Number of strings :”);
scanf(“%d”, &num);
printf(“Input string %d :\n”, num);
for(i=0;i<=num; i++)
{
fgets(name[i], sizeof name, stdin);
}
for(i=1;i<=num;i++)
for(j=0;j<=num-i;j++)
if(strcmp(name[j],name[j+1])>0)
{
strcpy(temp,name[j]);
strcpy(name[j],name[j+1]);
strcpy(name[j+1],temp);
}
printf(“The strings appears after sorting :\n”);
for(i=0;i<=num;i++)
printf(“%s\n”,name[i]);
}

25) Write code in C to print “hello world” without using a semicolon

 #include<conio.h>
#include<stdio.h>
void main()
{
if(printf(“hello world”))
{
}
}

Output:

hello world

26) Write a program to find factorial of a number.

#include<conio.h>
#include<stdio.h>
Void main()
{
int i, fact=1, num;
clrscr();
printf(“Enter the number for which you want to find factorial\n”);
scanf(“%d”, &num);
for(i=1;i<=num; i++)
{
fact=fact*i;
}
printf(“Factorial of %d is : %d”,num,f);
return 0;
}

27) Write a C program for Fibonacci series.

#include<stdio.h> 
#include<conio.h>   
int main()
{
 int n1=0,n2=1,n3,i,number;
 printf(“Enter the number of elements:”);
 scanf(“%d”,&number);
 printf(“\n%d %d”,n1,n2);  //printing 0 and 1    
 for(i=2;i<number;++i)    //loop starts from 2 because 0 and 1 are already printed    
 {
  n3=n1+n2;
  printf(” %d”,n3);
  n1=n2;
  n2=n3;
 }
  return 0;
 }

28) What is the logic behind reverse of a string in java?

The reverse of a string:

import java.util.*;
class ReverseString
{
public static void main(String parvez[])
{
String original, reverse= ” “;
Scanner in=new scanner(system.in);
System.out.println(“Enter the string: “);
original= in.nextLine();
int length=original.Length();
for(i=length-1;i>=0;i–)
reverse=reverse+original.charAt(i);
System.out.println(“Reversed string: “ +reverse);
}
}

Output:

Enter the string: parvez
Reverse string: zevrap

29) Name the operators that can’t be overloaded.

These are the following operators that can’t be overloaded.

Scope Resolution operator (::)
Pointer-to-member Operator (.*)
Member Access or Dot Operator (.)
Ternary or conditional operator (?:)
Object size Operator (sizeof)
Object type operator (typeid)

30) What is polymorphism?

In an object-oriented programming language, polymorphism is a characteristic which means one name with many forms.

We can say that polymorphism shows different behavior in a different scenario.

There are two types of Polymorphism.

Compile time polymorphism: It is known as method overloading.
Runtime polymorphism: it is also known as method overriding.

31) How is C++ struct different from C++ class?

A struct is a bundle. It is a combination of all related elements that need to work together in a particular context. Such as, the restricted number of arguments context can pass to a function:

If you don’t specify the access modifier, visibility (public, private or protected) of the members will be public in the struct and private in the class.

The visibility by default goes just a little further than members: for inheritance, if you don’t specify anything then the struct will inherit publicly from its base class, while the class will do private inheritance:

32) What is DOM?

DOM stands for Document Object Model. It is a programming API for the HTML and XML documents. DOM provides the logical structure of the document and the way in which a document is accessed and manipulated.

DOM represents a table in the hierarchical form.

33) Specify the characters which can be used as the second character of an identifier, but not as the first character of an identifier?

Any number within the range of 0 to 9 can be taken as the second character of an identifier, but as per restriction, it can’t be treated as the first character on an identifier.

34) What Is The List Interface?

List Interface is the subinterface of Collection. It contains methods to insert and delete elements on an index basis. It is a factory of List-Iterator interface. Lists may contain duplicate items. The List interface includes operations for the following:

Positional Access: Manipulate elements based on their numerical position in the list.
Search: Search for specified objects in the list and return its numerical position.
List Iteration: Extend Iterator semantics to take advantage of the list’s sequential nature.
Range-view: Perform arbitrary range operations on the list.

List Interface declaration

public interface List<E> <strong>extends</strong> Collection<E>

35) What Is The Vector Class?

Vector implements List interface and maintains insertion order. Array list and vector class both are similar but with few differences.

Vector is synchronized: Vector is slow because it is synchronized, i.e., in multithreading environment; it will hold the other threads in runnable or non-runnable state until current thread releases the lock of the object.

Vector is a legacy class

Vector increments 100% means doubles the array size if the total number of elements exceeds than its capacity.

36) What is an Iterator Interface?

An iterator is a Java interface, and it has methods to iterate on elements of collections.

You can create your iterator object by calling iterator() method present in collection interface.

The methods of the interface are:

hasNext(): To know if any other elements left in the collection.
next (): Returns the next element.
remove (): To remove the current element from the collection(better not use that method).

37) What is the major difference between yield () and sleep ()?

Sleep () method in Java has two variants one which takes millisecond as sleeping time while other which takes both millisecond and nanosecond for the sleeping duration.

Yield () method pause all the currently executing thread, and give a chance to execute those threads or processes that need to be run. The current thread will continue to run again if no other thread is available to execute.

38) What Are Wrapped Classes?

Wrapper class in Java provides the mechanism to convert primitive into object and object into primitive. The eight classes of the java.lang package is known as wrapper classes in java.

The list of eight wrapper classes is given below:

Primitive Type	Wrapper class
Boolean	Boolean
Char	Character
Byte	Byte
Short	Short
Int	Integer
Long	Long
Float	Float
Double	Double

39) What is garbage collection? Does it guarantee that a program will not run out of memory?

Garbage collection:

Garbage Collection is a process of reclaiming the unused runtime memory automatically. i.e., it is a way to destroy the unused objects.

To do so, we were using free () function in the C language and delete () in C++. But, in Java, it is performed automatically. So, java provides better memory management.

In some cases, programs use up memory resources faster than they are garbage collected. We can also create objects “without new keyword” in programs that are not subject to garbage collection. That’s why garbage collection doesn’t guarantee that a program will not run out of memory.

40) What is the Name of the immediate superclass of the Applet class?

A panel is the immediate superclass of all Applet class.

The panel allows us to format the string.

A panel must have a specific layout out of FlowLayout, BorderLayout, GridLayout. If a Layout is not specified, then the default will be a FlowLayout.

41) What Is A Native Method?

The native is a keyword applied to a method to show that the method is implemented in Native Code (c, c++) using JNI (Java Native Interface). Hence, it is also known as foreign methods. It acts as an interface between Java Native Interface (JNI) and other programming languages.

It is a modifier that is not applicable to classes and objects. Native method declaration should compulsory ends with “;” because its implementation is already given.

42) What are the collections API?

The Collection in Java is a framework that provides an architecture to store and manipulate the group of objects.

All the operations that you perform on a data such as searching, sorting, insertion, manipulation, deletion, etc. can be achieved by Java Collections.

Java Collection means a single unit of objects. Java Collection framework provides many interfaces (Set, List, Queue, Deque, etc.) and classes (ArrayList, Vector, LinkedList, PriorityQueue, HashSet, LinkedHashSet, TreeSet, etc.)

Collection framework has:

Interfaces and its implementations, i.e., classes
Algorithm

43) List out some modifiers that may be used with an Inner class that is a member of an Outer class?

All the modifiers such as

public
private
abstract
final
protected
strictfp
static
default

44) What is the name of the method of the component class which is used to set the position and size of a component?

setBounds () method is having four coordinates (x, y, width, height) to specifying the position and size of a GUI component .

45) Which Java.util Classes and Interfaces Support Event Handling?

java.awt.event.*; Support event handling.

46) How many number of bits are used to represent a character in Unicode, ASCII, UTF-32, UTF-16, And UTF-8 characters?

Unicode requires 16 bits (2 bytes) to represent a character, ASCII requires 7 or 8 bits, and UTF-8 requires 8, 16 and 18-bit pattern.

UTF=16 requires 16 bits and 32 bits pattern.

UTF-32 requires 32 bits pattern

47) What are the restrictions for the location of a package statement within a source code file?

Restriction for the package:

A package must be appeared in the first line of the program source code, excluding blank lines and comments.

48) What are the major differences between preemptive scheduling and time slicing?

Preemptive scheduling:

Under primitive scheduling, the highest priority task executes until it enters the waiting or dead states or any other higher priority task comes into existence.

Time slicing:

Time slicing: A task executes for a fixed period of time and then reenters again in the pool of ready tasks to execute the remaining task later. The scheduler then determines that which task should execute next, based on priority and other factors.

49) Give the name of three component subclasses that support painting.

The canvas class, the Frame class, and Applet class are the subclasses which support painting.

50) When a Readline () reach at the end of file then what will it return?

Readline() will return a null value when it would reach at the end of the file.

51) What is the name of the immediate superclass of the Dialog class?

The window class is the immediate superclass of Dialog class.

52) Define Order of precedence and Associativity, how are they used?

Order of precedence is used with the operators. When a number of operators are used in an expression, it evaluates with the priority of the operators.

Associativity is used to check whether an expression is evaluated from left-to-right or right-to-left.

Order of precedence example:

(5 > 2 + 5 && 4)

The given expression is equivalent to:

((5 > (2 + 5)) && 4)

The expression (2 + 5) will executes first and the result will be 7
Then after first part of the expression (5 > 7) executes and gives 0 (false) as an output
Finally, (0 && 4) executes and gives 0 (false).

Associativity:

4 * 2 / 4

Here, operators * and / have the same precedence. Both “*” and “/” are left to right associative, i.e., the expression on the left is executed first and moves towards the right.

Thus, the expression above is equivalent to:

((4 * 2) / 4)
i.e., (4 * 2) executes first and the result will be 8 (true)
then, (8 / 4) executes and the final output will be 2 (true)

53) What is the rule for a catch or declare method declarations?

Catch block catches any exception that results from the try block. If a checked exception is thrown within the body of the method, the thrown exception must be caught by the method (with the help of try/catch block) or declare it in its throws clause.

54) What is the top class of the AWT Event Hierarchy?

java.awt.AWTEVENT class is the highest-level class of AWT event hierarchy.

55) When is a thread created and started, what is its initial state?

A thread is created and started with its Initial state called “ready” state where a thread is ready to run.

56) Is it possible to declare an anonymous class which implements an interface and extends a class?

Yes, an anonymous class can extend its superclass or implement an interface but cannot use both simultaneously.

57) Define Synchronization and why is it important?

Synchronization is a process which provides a feature by which access of multiple threads to any shared resource can control.

Hence, Java Synchronization is a better option for restriction. i.e., It allows only one thread to access the shared resource.

The synchronization is mainly used to

To prevent thread interference.
To prevent consistency problem.

58) Is Sizeof a Keyword?

Sizeof is an operator in C++ and a keyword in C, but it is not available in java.

59) What is a priority of task and how is it used in scheduling?

The entire task can’t execute simultaneously so that a scheduler assign priorities to all tasks for its execution. Priorities can be high or low depending on the task’s importance, and the integer values determine it.

Higher priority gets CPU for execution first.

60) Describe the three levels of data abstraction?

Data abstraction in DBMS is a process of hiding irrelevant details from users. Because database systems are made of complex data structures, so it makes accessible the user interaction with the database.

Following are three levels of data abstraction:

Physical level: It is the lowest level of abstraction. It describes how data are stored.

Logical level: It is the next higher level of abstraction. It describes what data are stored in the database and what the relationship among those data is.

View level: It is the highest level of data abstraction. It describes only part of the entire database.

61) What is Hashing technique in the data structure?

Hashing is a faster searching technique. The process of mapping a large amount of data item to a smaller table with the help of a hashing function is called hashing. In other words, hashing is a technique to convert a range of key values into a range of indexes of an array.

In terms of java: Hashing is a way to assign a unique code for any variable or object after applying any function or algorithm on its properties.