What is Programming?
Programming is simply creating a set of instructions for a computer to perform a specific task. Programming can be done using a variety of computer programming languages eg. Java, C++, C and the list is endless! The best part is, out of these very many options, you can go ahead with the language of your choice to implement the concepts in the form of a logical code.
Category of Programming Languages
Programming languages that have been developed so far can majorly be categorized into machine language, assembly language, and high-level language.
Machine Level Language:
A the name suggests, it is a low-level-language made up of binary numbers or bits that a machine/computer can understand. It is a sequence of 0s and 1s. It is also known as machine code or object code. any program that we write finally transforms into a sequence of s and 1s for the computer to understand.
Assembly Language:
Assembly language is intended to communicate directly with a computer's hardware. Unlike the usual machine language, which consists of binary characters, assembly language is expressed in a more human-readable form. In the future many of you are going to learn and program microprocessors in your higher studies or jobs; that would require an expertise in assembly language.
High-level Language:
It refers to the programming languages that allow the use of symbolic operators (to signify operations, eg. +,-,*,/ etc.) and symbolic names(to represent data and data structures, eg. variable names). They are also structured with syntax and semantics to describe the computing algorithm/program. This often requires the use of a compiler or an interpreter which helps in the translation from high-level human-understandable code into low-level machine code because the computer only works on the binary data. We will be learning and focussing on this category of language in our course. Before we move ahead, are you still confused about the differences between compiling and interpreting? Let us discuss this.
Compilation Vs Interpretation:
Compilation is the process to convert a high-level programming language into machine language (all at once) that the computer can understand. The software which performs this conversion is called a compiler.
Interpretation is performed by an Interpreter which directly executes instructions written in a programming or scripting language without previously converting them to an object code or machine code. This conversion of code happens line by line. Examples of interpreted languages are Perl, Python and Matlab.
Type of Programming Paradigms:
⮚ Procedural
⮚ Functional
⮚ Object Oriented
Procedural:
Consider a scenario where a program has to collect some data from users (read), perform some calculations (calculate), and then display the result(print) when requested; a simple example of this scenario is any online transaction that you/your parents do. In procedural approach, we can write 3 different procedures/functions for each of the operations of reading, calculating and printing (which could interact amongst each other as well). Hence, in the procedural approach:
The entire program code is organized as a set of procedures/functions or discrete blocks of codes that are executed in an order.
These procedures are also known as subroutines or functions and contain a series of steps that will be carried out when the procedure is called/used.
Some of the programming languages that enable us to use procedural approach : BASIC, FORTRAN, ALGOL, C, COBOL, and Pascal.
Functional:
Let's assume a scenario where we have to perform lots of different operations on the same set of data. This can be in the domains such as the web, statistics, financial analysis, and machine learning. Here, the functional programming paradigm helps a lot.
The program code is organized in pure functions(which always yield the same value for the same set of inputs without any deviation) with each function set up to perform a clearly defined task.
The data/variables are passed in the function as parameters (for the functions to interact with other functions or programs).
Languages that support this approach are: Javascript, Python, etc.
Object Oriented:
The program data is organized in classes and objects rather than functions and logic.
A class is a blueprint for creating objects and an object is referred to as an instance of a class that has unique attributes and behavior.
A good example of this could be you, yes you! You can be a ‘student’ or a ‘working professional’. In this scenario,under the class of ‘Person’, we can have a ‘Student’ or ‘Working professional’ class and you can be an instance of any of these based on whether you fall in the ‘student’ category or ‘working professional’ category. Hence, you are an object
Languages that support object-oriented approach include: Java, C++, C#, Python, R, PHP, Visual Basic.
The programming language that we are going to learn here is extremely simple yet very powerful! Any guesses ?! Yes, it's Java (we are already in the course, no marks for guessing!) Lets now, hit the bulls eye !! Let's get started.
Introduction to Java
Java is a general-purpose programming language created for developers (to write once and run anywhere) by James Gosling at Sun Microsystems later acquired by Oracle Corporation. The compiled Java code can run on all platforms that support Java. Java applications are compiled to byte code that can successfully run on any Java Virtual Machine (JVM). Syntax of Java is similar to C/C++. Java works on class-based and object-oriented approach of programming. It is one of the most widely used programming languages for creating desktop and mobile applications as well as big data processing and embedded systems.
Features of Java Programming
1. An Object-Oriented Language: Java is an object-oriented language because it is based on the concept of objects and classes (We will explore more about it once we start to code). Here, a complex problem is divided into smaller sets by using concepts of OOP. This makes Java code more understandable (closer to real-life implementation) and reusable. It also improves design and makes the code easier to maintain.
2. Java is platform independent: The Java code written on one platform can run successfully on other platforms without any modifications. It is not compiled into platform-specific machine code but into platform-independent byte code.
3. Simple and Secure: Java is designed to be easy to learn. If you understand the basic concepts of OOP, Java would be easy to master. It is one of the simplest languages as it does not have complex concepts like pointers, operator overloading, multiple inheritance, and explicit memory allocation (as we see in C++).
4. Large Standard Library: One of the reasons java is so famous is the availability of a huge standard library. To help software program builders like you (in future!), the Java environment carries and supports loads of classes and methods put into numerous packages.
Why is Java better than other programming languages?
Java has added advantages over other languages and environments that make it very appropriate for almost all programming errands. A few of them are :
1. Java syntax is simple to understand and easy to memorize since it is intuitive.
2. Java has been designed to be simpler to type,compile, debug, and learn than other programming languages.
3. Java is secure, convenient, viable and comes with superior high-level concurrency devices. Because of this, java is regularly the default choice for scientific applications, including natural language processing.
4. One of the coolest things about Java is its futuristic approach. When the whole world today is still stuck in Java 8 or Java 11, Oracle has already launched Java 18. The whole development community associated with java is very progressive which has kept it up to date since its inception.
Architecture
Before moving ahead with programming, we need to understand the architecture of Java with its components.
Java Architecture comprises of three major components viz. JVM, JRE, and JDK. Let us discuss each of these in brief.
JVM:- Java Virtual Machine or JVM, loads, verifies and executes Java bytecode (object code which is further converted into machine code). It is known as the interpreter or the core of Java programming language because it executes Java programming.The JVM manages system memory and provides a portable execution environment for Java-based applications. JVMs are available for many hardware and software platforms (i.e. JVM is platform dependent).
Examples: Hotspot,Eclipse OpenJ9
JRE:- The JRE is the underlying technology that communicates between the Java program and the operating system. It acts as a translator and facilitator, providing all the resources so that once you write Java software, it runs on any operating system without further modifications. A software program needs a runtime environment that provides access to memory and other system resources such as program files and dependencies. In the past, most software used the operating system directly as its runtime environment. However, this meant that developers had to write different code for each operating system that they wanted their applications to run on. The Java Runtime Environment (JRE) technology was created as a solution to this problem.
JDK:- The JDK is a collection of ‘software tools’ that you can use for developing Java applications. You can set up the JDK in your development environment by downloading and installing it. Select the JDK software version that matches the Java version you want to use. Still confused ! Let us look at the precise differences between the three. This
.png)
Installation Guide
For Windows
Content
🔘 Downloading and Installing JDK
🔘 Downloading and Installing IntelliJ Idea IDE
1. Click the link to download JDK or you may also go to link this website and download the latest version of java
_LI.jpg "Installation Guide Java For Windows")
Steps for installing IntelliJ ldea
1. Click on the link it will redirect you to the jetbrain website. Download the latest version of IntelliJ idea from Community section.
_LI.jpg "Steps for installing IntelliJ ldea")
2. Keep pressing ‘next’ without changing any of the default settings and you will land on this screen.
.png)
3. Check the options as shown in the image and proceed with ‘Next’ button.
4. To complete the installation, reboot/restart your system.
When you open IntelliJ from the icon, this screen will appear
_LI.jpg)
.png)
Installation Completed
JDK: - JDK
stands for java development kit, it internally contains JRE & JVM where JRE
stands for Java runtime environment and JVM stands for java virtual machine.
JDK provides all the tools to work with java language.
JRE: - JRE
stands for java runtime environment, it provides an environment to execute the
java program. It internally contains JVM which is responsible to execute a Java
Program.
JVM: - JVM
Stands for java virtual machine, it is the software in the form of interpreter
written in ‘C’ language through which we can execute our java program.
What is
JAVA? With Syntax & Example.
Java is a class based high-level object-oriented programming
languages developed by “James goslig” and his friends in the year 1991.
The
first version of java (JDK 1.0) was released on the year 23rd jan,
1996 by sun microsystem.
Syntax: -
Class
class-name
{
public
static void main(String arg[])
{
System.out.print(“ “);
}
}
Rule: -
1.
Save -> class_name.java
2.
Compilation -> javac class_name.java
3.
Execution -> java class_name
Example: -
Class A
{
public
static void main(String[]a)
{
System.out.print(“welcome
java”);
}
}
Java
History
·
java is a totally computer-based programming
language developed by sun microsystem (james gosling, mike Sheridan & patrich
Naughton).
·
In the year 1991 James Gosling & his friend
Start a project.
Team -> Green team
·
James Gosling -> greentalk
Extension -> .gt
·
Greentalk -> oak
·
Oak -> Java (1995)
·
Java -> Setbox, television, remote etc….
·
Java -> internet programming
·
Version -> JDK alpha & Beta, 1995 (By Sun
Microsystem).
·
Latest Version -> JDK 15 (2020, Oracle)
·
Sun Microsystem -> Oracle corporation, 2010
JAVA: -
Core
JAVA
Advance
JAVA
Android
JAVA
Features of
Java
1.
Object oriented
2.
Platform independent
3.
Simple language
4.
Secure
5.
Portable
6.
Compiled & interpreted
7.
Robust
8.
Distributed
9.
Multi-threaded
10.
Performance
11.
Dynamic
class A
{
public
static void main(String args[])
{
}
}
class A
{
public
static void main(String[] args)
{
System.out.println(“Hello
World”);
}
}
________________________________________________________
Class A
void
show()
{
System.out.println(“hello
india”);
{
public
static void main(String []args)
{
A
ref=new A();
ref.show();
System.out.println(“Welcome
java”);
}
}
___________________________________________________
Class A
static
void show()
{
System.out.println(“hello
india”);
{
public
static void main(String []args)
{
A.show();
System.out.println(“Welcome
java”);
}
}
What is
comment? Full explanation.
Comment are the statements that are totally ignored by the
compiler & interpreter.
Why We use
comment: -
1.
The comments can be used to provide explanation
about the program.
2.
Comments makes program move understandable and
redable to the other programmer.
Type of
comment: -
1.
Single line comment Ã
// statements
2.
Multiline comment Ã
/* statements */
3.
Documentation Ã
/** statements */
/*Java Variable*/
Class test
{
int a=10; // instance variable
static int b=20; //static variable
public static void main(String[]
args)
{
Int
c=30; //local variable
Final
int D=40; //final variable
Test
t=new Test(); //object variable
System.out.println(t.a);
System.out.println(b);
System.out.println(c);
Systme.out.println(D);
}
}
Data type:
-
Datatype specify the different sizes & values that can
be stored in the variable.
|
Datatype |
|
Primary(primitive) |
|
User-defined(non-primitive) |
|
Numeric |
|
Non-numeric |
|
integric |
|
Decimal |
|
Byte (1) byte |
|
Short (2) |
|
Int (4) |
|
Long (8)
|
|
Float (4) |
|
Double (8) |
|
Char (2) |
|
Boolean (1 bit) |
|
class |
|
interface |
|
arrays |
|
String |
What is
variable? Discuss with Types.
Variable Is the name of memory location. in other word we
can say it is user defined name which is given by user. Variable can store any
types of values.
Type of
Variable: -
1.
Local
2.
Static
3.
Instance
Local
Variable: - A variable which is declared inside the body of the
method or method parameter called local variable.
Instance
Variable: - A variable which is declared inside the class but
outside of all the methods called instance variable.
Static
Variable: - A variable which is declared with the help of static
keyword called static variable.
Example: -
class A
{
static int
b=20;//static
int
c=30;//instance
public
static void main(string[]args)
{
int
a=10;/local
A
ref=new A();
System.out.println(a);
System.out.println(A.b);
System.out.println(ref.c);
}
}
class try
{
static
int a=10;
void
fun()
{
int
b=10;
System.out.println(a+” “+b);
++a; ++b;
}
public
static void main(String[] args)
{
A
r=new A();
r.fun();
r.fun();
}
}
Add two
number without user input
class add
{
public
static void main(String [] args)
{
int
num1=30,num2=40;
int
sum=num1+num2;
System.out.println(sum);
}
}
What is
typecasting? With type.
Converting one datatype to another datatype is called
typecasting.
Type: -
1.
Implicit
2.
Explicit
Implicit: -
It is automatically performed by the compiler.
// Implicit
Typecasting.......
class implicit
{
public
static void main(String [] args)
{
int
a=10; //4 bytes
double
b=a; //8 bytes
System.out.println(b);
}
}
Explicit
Typecasting: -
By default, the compiler, doesn’t allow the explicit
typecasting.
// Explicit
Typecasting.......
class explicit
{
public
static void main(String [] args)
{
double
a=10.5;
int
b=(int)a;
System.out.println(b);
}
}
Input (Scanner
class): -
Scanner is a pre-defined class in java which is available in
java.util package. It is used to get user input.
Rule 1: -
If we
use Scanner class, must have to create object of Scanner class.
Syntax: -
Scanner
object_name=new Scanner(System.in);
Rule 2: -
Scanner class methods: -
1.
nextLine(); //String
2.
nextInt(); //integer
3.
nextFloat(); //floating
4.
nextBoolean(); //true
or false
5.
nextDouble(); //double
Rule 3: -
import Scanner class package of
the top line of program: -
Syntax:
- import java.util Scanner;
Rule 4: -
Wrong input (Input mismatch
Exception)
Output: -
(System.out.print())
It is an output statement in java through which we can print
the variables, expressions and many more contents.
System: - 1.
Pre-defined class.
InputOutput
Program: -
import java.util.Scanner;
class inputOutput
{
public
static void main(String [] args)
{
int
a;
System.out.println("Enter
value of a");
Scanner
obj=new Scanner(System.in);
a=obj.nextInt();
System.out.println("Value
of a is "+a);
}
}
import java.util.Scanner;
class userInput
{
public
static void main(String[]args)
{
int
a,b;
Scanner
obj=new Scanner(System.in);
System.out.print("Enter
value of a ");
a=obj.nextInt();
System.out.print("Enter
value of b ");
b=obj.nextInt();
System.out.print("sum
of two number is "+(a+b));
}
}
What is
Token? Full explanation.
Token is the smallest elements of a program that is
identified by a compiler.
Every
java statements and expression are created using tokens.
Token: -
1.
Keywords ex:
- int, static, void
2.
Identifiers ex:
- variable, method, class_name
3.
Operator ex:
- +, -, *, /, %, &&, ||, ++, --
4.
Separator ex:
- ;
, . : ()
5.
Literal
What is
keyword? Full explanation.
Keyword’s are the reserved word whose meaning is already
defined in the compiler called keywords.
Java
Keyword’s: -
|
abstract |
continue |
for |
new |
switch |
|
assert*** |
default |
goto* |
package |
synchronized |
|
boolean |
do |
if |
private |
this |
|
break |
double |
implements |
protected |
throw |
|
byte |
else |
import |
public |
throws |
|
case |
enum**** |
instanceof |
return |
transient |
|
catch |
extends |
int |
short |
try |
|
char |
final |
interface |
static |
void |
|
class |
finally |
long |
strictfp** |
volatile |
|
const* |
float |
native |
super |
while |
|
* |
|
not used |
|
** |
|
added in 1.2 |
|
*** |
|
added in 1.4 |
|
**** |
|
added in 5.0 |
Note: -
1.
True, false and null just like keywords, but
they are actually literals.
2.
You can’t use any of the following as
identifiers in your programs.
What is
identifier? Full explanation.
In java, an identifier is the name of a variable, method,
class, package or interface that is used for the purpose of identification.
Rule of
identifier: -
1.
Keyword can’t be used as a identifier.
2.
Identifier are case-sensitive.
3.
We can’t use whitespace in between identifier.
4.
Identifier always start with letters, $ or _
(underscore).
What is
operators? With types.
Operator is a symbol that Is used to perform operations
according to user requirement. (variable & values)
Types: -
1.
Arithmetic (+, - ,*, /, %)
2.
Relational (<, >, <=, >=, !=, ==)
3.
Logical (&&, ||, !)
4.
|
Unary |
5.
a.
Simple (=)
b.
Compound (+=, -=, *= etc)
6.
Ternary (? :)
7.
Bitwise(AND, OR, XOR, COMPLEMENT)
//
Arithmetic Operator Example......
import java.util.Scanner;
class arithmetic
{
public
static void main(String [] args)
{
int
a,b;
Scanner
obj=new Scanner(System.in);
System.out.print("Enter
two number: ");
a=obj.nextInt();
b=obj.nextInt();
System.out.println("Addition
"+(a+b));
System.out.println("Subtract
"+(a-b));
System.out.println("Multiply
"+(a*b));
System.out.println("Divide
"+(a/b));
System.out.println("Modulo
"+(a%b));
}
}
//
Relational Operator Example.........
import java.util.Scanner;
class relational
{
public
static void main(String [] args)
{
int
a,b;
Scanner
obj=new Scanner(System.in);
System.out.println("Enter
two number: ");
a=obj.nextInt();
b=obj.nextInt();
System.out.println("false/true
(a<b) "+(a<b));
System.out.println("false/true
(a>b) "+(a>b));
System.out.println("false/true
(a<=b) "+(a<=b));
System.out.println("false/true
(a>=b) "+(a>=b));
System.out.println("false/true
(a!=b) "+(a!=b));
System.out.println("false/true
(a==b) "+(a==b));
}
}
//Logical
Operator Example............
class logical
{
public
static void main(String []args)
{
System.out.println("Logical
AND");
System.out.println((10>5)&&(2>1)); //true
System.out.println((10>5)&&(2<1)); //false
System.out.println((10<5)&&(2<1)); //false
System.out.println("Logical
OR");
System.out.println(10>5||(2>1)); //true
System.out.println(10>5||(2<1)); //true
System.out.println(10<5||(2<1)); //false
System.out.println("Logical
NOT");
System.out.println(!(10>5)); //false
System.out.println(!(10<5)); //true
}
}
//Increment/Decrement
Operator Example................
class incrdecr
{
public
static void main(String []args)
{
int
a=10;
System.out.println(a);
System.out.println("PrePost
increment...");
System.out.println(a++);
System.out.println(++a);
System.out.println("PrePost
decrement...");
System.out.println(a--);
System.out.println(--a);
}
}
//
Assignment Operator Example.......
class assignment
{
public
static void main(String [] arts)
{
int
a=10;
System.out.println(a);
a+=10;//
a=a+10;
System.out.println(a);
a-=10;//
a=a-10;
System.out.println(a);
}
}
// Ternary
Operator Example.....
class Ternary
{
public
static void main(String []args)
{
int
a=10,b=20,max;
max=(a>b)?a:b;
System.out.print(max);
}
}
// Bitwise
Operator Example......
class bitwise
{
public
static void main(String [] args)
{
int
a=5,b=7;
System.out.println("AND
"+(a&b));
System.out.println("OR
"+(a|b));
System.out.println("XOR
"+(a^b));
System.out.println("Complement
"+(~a));
}
}
Decision
Making: -
1. If statement
a.
Simple if
b.
If-else
c.
If else ladder
d.
Nested if-else
2. Switch Statement
Simple if
statement: -
è
It is used when we want to test a condition.
Syntax: - if(condition)
{
}
Example: -
// Simple If Statement
import java.util.Scanner;
class simpleIf
{
public
static void main(String []a)
{
int
age;
Scanner
r=new Scanner(System.in);
System.out.println("Enter
your age: ");
age=r.nextInt();
if(age>=18)
{
System.out.println("Eligible
for vote");
}
System.out.print("thank
u");
}
}
If-else
statement: -
It is used to execute two statements either if statement or
else statement for a single condition.
Syntax: -
If(condition)
{
}
Else
{
}
Example: -
//if-else statement............
import java.util.Scanner;
class ifElse
{
public
static void main(String a[])
{
int
num;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number: ");
num=r.nextInt();
if(num>0)
{
System.out.println("+ve
number");
}
else
{
System.out.print("-ve
number");
}
}
};
else-if
ladder statement: -
It is used when we have only one if block, multiple else-if
blocks and at last one else block.
Syntax: -
If(condition)
{
}
Else if(condition)
{
}
Else if(condition)
{
}
Else
{
}
Example: -
//else-if ladder statement
import java.util.Scanner;
class elseIf
{
public
static void main(String[] args)
{
int
marks;
Scanner
obj=new Scanner(System.in);
System.out.print("Enter
your marks: ");
marks=obj.nextInt();
if(marks>80)
{
System.out.print("Topper");
}
else
if(marks<80 && marks>60)
{
System.out.print("first");
}
else
{
System.out.print("second");
}
}
};
Nested if
else statement: -
Whenever we define if else block, inside this if else block
we define another if else block is called nested if else statement.
Syntax: -
If(condition)
{
If(condition)
{
}
Else
{
}
Else
{
If(condition)
{
}
Else
{
}
}
Example: -
//Nested if else statement…….
import java.util.Scanner;
class nestedIf
{
public
static void main(String[]args)
{
int
a,b,c;
Scanner
r=new Scanner(System.in);
System.out.println("Enter
three number: ");
a=r.nextInt();
b=r.nextInt();
c=r.nextInt();
if(a>b)
{
if(a>c)
{
System.out.print("greatest
number is "+a);
}
else
{
System.out.print("greatest
number is "+c);
}
}
else
{
if(b>c)
{
System.out.print("greatest
number is "+b);
}
else
{
System.out.print("greatest
number is "+c);
}
}
}
}
Switch
statement: -
Switch is a multiple-choice decision-making selection
statement, it used when we want to select only one case out of multiple cases.
Syntax: -
Switch(expression)
{
Case
1:
Statement1;
Break;
Case
2:
Statement
2;
Break;
Case
n:
Statement
3;
Break;
Default:
Statement;
}
Example: -
import java.util.Scanner;
class Swithc
{
public
static void main(String[]args)
{
int
a=10,b=20,ch;
Scanner
r=new Scanner(System.in);
System.out.println("Enter
your choice: ");
ch=r.nextInt();
switch(ch)
{
case
1:
System.out.println("Sum
is "+(a+b));
break;
case
2:
System.out.println("Subtract
is "+(a-b));
break;
case
3:
System.out.println("Sum
is "+(a*b));
break;
case
4:
System.out.println("Sum
is "+(a/b));
break;
default:
System.out.println("invalid
choice.....!");
}
}
}
Looping
Statement: -
è
Whenever we have to repeat certain statement
several times is called loop.
Advantage:
-
1.
Fast execution
2.
Reusability
3.
Decrease line of code
4.
Memory space less
Type: -
There are four type of loop
1. While loop
2. Do-while loop
3. For loop
4. For each loop
1.
While loop:
-
è
While loop is a pre-test loop, it is used when
we don’t know the no of iteration in advance.
è
It is also known as entry control loop.
Syntax: -
While(condition)
{
Statement;
}
Example: -
class loop
{
public
static void main(String[]args)
{
int
n=1;
while(n<=10)
{
System.out.println("Hello
mr. Hemant Kumar");
++n;
}
}
}
2.
Do-while
loop: -
è
Do-while loop is a post-test loop, it is used
when we want to execute loop body atleast once even condition is false.
è
It is also known as exit control loop.
Syntax: -
Do
{
Statement;
}
While(condition);
Example: -
/* do while loop statement */
class dowhile
{
public
static void main(String[]arts)
{
int
n=1;
do
{
System.out.println(n+"
");
++n;
}
while(n<=10);
}
}
3.
For loop: -
è
For loop is the most commonly used loop, it is
used when we want to perform initialization, condition and increment/decrement
operation in single line.
Syntax: -
for(initialization;condition;increment/decrement)
{
Statement;
}
Example: -
// for loop example......
class for1
{
public
static void main(String[]args)
{
for(int
i=1;i<=10;i++)
{
System.out.println(i);
}
}
}
For each
loop: -
For each loop mainly used to fetch the values from a collection
like array.
Syntax: -
for(data_type var1 : var2)
{
Statement;
}
Example: -
// for each loop example......
class forEach
{
public
static void main(String[]args)
{
int
a[]={10,20,30,40,50,60,70,80,90,100};
for(int
b : a)
{
System.out.println(b);
}
}
}
Nested for
loop: -
è
A for loop which contain inside another for loop
is called nested for loop.
Syntax: -
For(initialization; condition;updation)
{
For(initialization;
condition; updation)
{
}
}
Example: -
// nested for loop
example.......
class nested_for
{
public
static void main(String[]args)
{
int
i,j;
for(i=1;i<=5;i++)
{
for(j=1;j<=5;j++)
{
System.out.print("*
");
}
System.out.println();
}
}
}
Java MCQ’S
1.
Who is the
Developer of java?
a)
Dennis
Ritchie
b)
James Gosling
c)
Bjarne
Stroustrup
d)
Charles
Babbage
2.
What was
java name Before?
a) Java
b) Javax
c) Classes and java
d) Oak
3.
In which
year java was Developed?
a) 1991
b) 1972
c) 1979
d) 1995
4.
What is the
extension of java?
a) .gt
b) .oak
c) .java
d) .exe
5.
Java was
Developed by_________________?
a) Sun
MicroSystems
b) Oracle
c) Microsoft
d) ANSI
6.
Which of
the following are flavours of java?
a) J2SE
b) J2EE
c) J2ME
d) All of above
7.
Whose
product is java right now?
a) Sun MicroSystems
b) Microsoft
c) ANSI
d) Oracle
8.
What is the
first version of java?
a) JDK alpha &
Beta
b) JDK 1.0
c) JDK 15
d) All of above
9.
What is the
compilation process of java program?
a) Java class_name.java
b) Javac
class_name.java
c) Javac class_name
d) Class_name.java
10.What is the Execution process of java program?
a) Java class_name
b) Javac class_name
c) Class_name.java
d) Class_name java
11.In java, JDK stands for_____________?
a) Java Design Kit
b) Java Developer Kit
c) Java
Development Kit
d) None of these
12.In java, JRE stands for_______________?
a) Java Running Environment
b) Java Runtime
Environment
c) Java Runtime Execution
d) None of these
13.In java, JVM stands for_______________?
a) Java Virtual
Machine
b) Java Verification Machine
c) Java virtual Moment
d) None of these
14.Which of the following is features of java?
a) Platform independent
b) Simple & secure
c) Dynamic
d) All of above
15.In java, system class is defined in __________?
a) Java.Util package
b) Java.lang
package
c) Java.io package
d) None
16.In java, Scanner class is defined in ___________?
a) Java.util
package
b) Java.lang package
c) Java.io package
d) All of above
17.In java, Scanner class is used to take input at___________?
a) Compile-time
b) Run-time
c) Both a & b
d) None
18.Which Stream is used for output?
a) System.out
b) System.in
c) Scanner
d) none
19.Which Scanner class method is used to read integer value?
a) nextInt()
b) next()
c) readInt()
d) nextInteger()
20.which Scanner class method is used to read String value?
a) nextLine()
b) next()
c) readString()
d) Both a & b
21.How many types of datatype in java?
a) One
b) Two
c) Three
d) None
22.How many primitive datatypes in java?
a) 4
b) 6
c) 7
d) 8
23.What is the size of char datatype?
a) 1 byte
b) 2 bytes
c) 4 bytes
d) None
24.What is the default value of Boolean datatype?
a) True
b) False
c) True/false
d) None
25.Which of the following is smallest integer datatype?
a) Short
b) Int
c) Long
d) Byte
26.Which of the following datatypes comes under floating datatypes?
a) Long
b) Double
c) Float
d) Both b & c
27.What is the range of byte datatype is?
a) -128 to 128
b) -127 to 128
c) -128 to 127
d) -127 to 127
28.How many loops are their in java?
a) Two
b) Three
c) Four
d) None
29.Which loop always execute atleast once, even condition is false?
a) While loop
b) Do while loop
c) For loop
d) For-each loop
30.Do while loop is also known as ________loop?
a) Entry control
b) Exit control
c) Both a & b
d) None
31.Which of the following loops are entry-controlled loop?
a) While
b) Do while
c) For loop
d) Both a & c
32. What is the purpose for using loop?
a) For repetition
b) Check condition
c) Finding errors
d) None
33. Which loop is best suitable for arrays in java?
a) For loop
b) For-each loop
c) While loop
d) Do while loop
34. Which of following is not a part of binary operator?
a) Assignment
operator
b) Arithmetic operator
c) Relational operator
d) Logical operator
35. Which of following is not a arithmetic operator?
a) +
b) *
c) %
d) &
36. How many types of logical operators?
a) Two
b) Three
c) Four
d) None
37.Relational operator is used for?
a) Comparison
b) Assignment
c) Finding errors
d) All of above
38. Which of the following is bitwise AND operator?
a) &&
b) ||
c) !
d) &
39. Which operator is used for alternate of if-else statement?
a) Arithmetic operator
b) Bitwise operator
c) Ternary
operator
d) Incr/Decr oprator
40. What is the default value of static variable?
a) 0
b) 1
c) Garbage
d) None
41. A variable which is declared inside the method called___________?
a) Instance variable
b) Local variable
c) Static variable
d) None
42. Which of these selection statements test only for equality?
a) If
b) Switch
c) If &switch
d) None
43. If statement execute of skip statement depending on
the__________expression?
a) Boolean
b) Double
c) Integeric
d) None
Programming Questions
//odd even
program
import java.util.Scanner;
class oddEven
{
public
static void main(String[]args)
{
int
n;
System.out.print("Enter
a number: ");
Scanner
r=new Scanner(System.in);
n=r.nextInt();
if(n%2==0)
{
System.out.print("number
is even ");
}
else
{
System.out.print("number
is odd ");
}
}
}
// to print
first N natural numbers program
import java.util.Scanner;
class natural
{
public
static void main(String[]args)
{
int
n;
System.out.print("Enter
a number ");
Scanner
r=new Scanner(System.in);
n=r.nextInt();
for(int
i=1;i<=n;i++)
{
System.out.print(i+
" ");
}
}
}
// Sum of
first N natural numbers program
import java.util.Scanner;
class naturalSum
{
public
static void main(String[]args)
{
int
n,sum=0;
System.out.print("Enter
a number ");
Scanner
r=new Scanner(System.in);
n=r.nextInt();
for(int
i=1;i<=n;i++)
{
sum=sum+i;
}
System.out.println("Sum
is " +sum);
}
}
//print all
odd numbers between 1 to N
import java.util.Scanner;
class odd
{
public
static void main(String []args)
{
int
n;
System.out.print("Enter
a number: ");
Scanner
r=new Scanner(System.in);
n=r.nextInt();
for(int
i=1;i<=n;i+=2)
{
System.out.print(i+"
");
}
}
};
//print all
odd numbers between 2 to N
import java.util.Scanner;
class even
{
public
static void main(String []args)
{
int
n;
System.out.print("Enter
a number: ");
Scanner
r=new Scanner(System.in);
n=r.nextInt();
for(int
i=2;i<=n;i+=2)
{
System.out.print(i+"
");
}
}
};
//calculate
sum of odd or even numbers
import java.util.Scanner;
class sumOddEven
{
public
static void main(String[]args)
{
int
n,sumEven=0,sumOdd=0;
System.out.print("Enter
a number: ");
Scanner
r=new Scanner(System.in);
n=r.nextInt();
for(int
i=1;i<=n;i++)
{
if(i%2==0)
{
sumEven=sumEven+i;
}
else
{
sumOdd=sumOdd+i;
}
};
System.out.println("Sum
of Even is "+sumEven);
System.out.println("Sum
of Odd is "+sumOdd);
}
}
//take
character input from user
import java.util.Scanner;
class charprint
{
public
static void main(String[]args)
{
char
ch;
System.out.print("Enter
a character:");
Scanner
r=new Scanner(System.in);
ch=r.next().charAt(0);
System.out.print(ch);
}
}
//check
character is vowel or consonant
import java.util.Scanner;
class vowel
{
public
static void main(String[]args)
{
char
ch;
System.out.print("Enter
a character: ");
Scanner
r=new Scanner(System.in);
ch=r.next().charAt(0);
if(ch=='a'||ch=='A'||ch=='e'||ch=='E'||ch=='i'||ch=='I'||ch=='o'||ch=='O'||ch=='u'||ch=='U')
{
System.out.print("Vowel");
}
else
{
System.out.print("consonent");
}
}
}
//print
ASCII value of character.
import java.util.Scanner;
class ascii
{
public
static void main(String []args)
{
char
ch;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a character: ");
ch=r.next().charAt(0);
int
a=ch;
System.out.print("ASCII
value is "+a);
}
}
//print A
to Z alphabets
import java.util.Scanner;
class alpha
{
public
static void main(String[]args)
{
for(char
i='A';i<='Z';i++)
{
//char
ch=i;
System.out.print(i+"
");
}
}
}
//find greatest
number between two numbers.
import java.util.Scanner;
class big
{
public
static void main(String [] args )
{
int
num1,num2;
System.out.print("Enter
two numbers: ");
Scanner
h=new Scanner(System.in);
num1=h.nextInt();
num2=h.nextInt();
if(num1>num2)
{
System.out.print(num1+"
is greatest number");
}
else
{
System.out.print(num2+"
is greatest number");
}
}
}
//calculate
power of a number.
import java.util.Scanner;
class power
{
public
static void main(String []args)
{
Scanner
r=new Scanner(System.in);
int
p,b,result=1;
System.out.print("Enter
value of base: ");
b=r.nextInt();
System.out.print("Enter
value of power: ");
p=r.nextInt();
for(int
i=1;i<=p;i++)
{
result=result*b;
}
System.out.print("result="+result);
}
}
// Find
greatest number among three numbers.
import java.util.Scanner;
class greatest
{
public
static void main(String[]args)
{
int
a,b,c;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
first number: ");
a=r.nextInt();
System.out.println("Enter
second number: ");
b=r.nextInt();
System.out.println("Enter
third number: ");
c=r.nextInt();
if(a>b)
{
if(a>c)
{
System.out.print("greatest
number is "+a);
}
}
else
{
if(b>c)
{
System.out.print("greatest
number is "+b);
}
else
{
System.out.print("greatest
number is "+c);
}
}
}
}
//calculate
average marks of five subjects.
import java.util.Scanner;
class average
{
public
static void main(String []args)
{
int
math,hindi,eng,sci,sst,average;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
five subject marks: ");
math=r.nextInt();
hindi=r.nextInt();
eng=r.nextInt();
sci=r.nextInt();
sst=r.nextInt();
average=(math+hindi+eng+sci+sst)/5;
System.out.print("average="+average);
}
}
// find
factorial of a number.
import java.util.Scanner;
class fact
{
public
static void main(String []args)
{
int
fact=1,num;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number: ");
num=r.nextInt();
for(int
i=1;i<=num;i++)
{
fact=fact*i;
}
System.out.print("Result="+fact);
}
}
//count
number of digits.
import java.util.Scanner;
class digit
{
public
static void main(String []args)
{
int
num,count=0;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a nmuber: ");
num=r.nextInt();
while(num!=0)
{
num=num/10;
count++;
}
System.out.print("total
number of digits is "+count);
}
}
// print
multiplication table.
import java.util.Scanner;
class table
{
public
static void main(String[]args)
{
int
n;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number: ");
n=r.nextInt();
for(int
i=1;i<=10;i++)
{
System.out.println(n+"*"+i+"="+n*i);
}
}
}
//tax
calculation program.
import java.util.Scanner;
class tax
{
public
static void main(String []args)
{
int
salary;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
Salary: ");
salary=r.nextInt();
if(salary<=10000)
{
System.out.print("salary="+salary+"
No tax");
}
else
if(salary>=10000&&salary<=100000)
{
double
tax;
tax=salary*0.10;
System.out.print("salary="+tax+"
with tax");
}
else
{
double
tax;
tax=salary*0.20;
System.out.print("salary="+tax+"
with tax");
}
}
}
// swap of
two number.
import java.util.Scanner;
class swap
{
public
static void main(String[]args)
{
int
a,b,c;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
first number: ");
a=r.nextInt();
System.out.print("enter
second number: ");
b=r.nextInt();
c=a;
a=b;
b=c;
System.out.print("a="+a+"
b="+b);
}
}
// swap of
two numbers without using third variable.
import java.util.Scanner;
class swapwithout
{
public
static void main(String[]args)
{
int
a,b,c;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
first number: ");
a=r.nextInt();
System.out.print("enter
second number: ");
b=r.nextInt();
a=a+b;
b=a-b;
a=a-b;
System.out.print("a="+a+"
b="+b);
}
}
// check
number is positive or negative......
import java.util.Scanner;
class pos_neg
{
public
static void main(String[]args)
{
int
a;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number : ");
a=r.nextInt();
if(a>0)
{
System.out.print("positive
number "+a);
}
else
if(a==0)
{
System.out.print("niether
negative or positive number "+a);
}
else
{
System.out.print("negative
number "+a);
}
}
}
// check
number is divisible by 5 or Not.....
import java.util.Scanner;
class divi
{
public
static void main(String[]args)
{
int
n;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number : ");
n=r.nextInt();
if(n%5==0)
{
System.out.print("Number
is divisible by 5");
}
else
{
System.out.print("Number
is not divisible by 5");
}
}
}
// find
factor of a number....
import java.util.Scanner;
class factor
{
public
static void main(String[]args)
{
int
n;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number : ");
n=r.nextInt();
for(int
i=1;i<=n;i++)
{
if(n%i==0)
{
System.out.print(i+"
");
}
}
}
}
// Reverse
a Number
import java.util.Scanner;
class reverse
{
public
static void main(String[]args)
{
int
n,m,rev=0;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number: ");
n=r.nextInt();
while(n!=0)
{
m=n%10;
rev=rev*10+m;
n=n/10;
}
System.out.print("Reverse
number is "+rev);
}
}
// Reverse
a Number
import java.util.Scanner;
class sumof
{
public
static void main(String[]args)
{
int
n,m,sum=0;
Scanner
r=new Scanner(System.in);
System.out.print("Enter
a number: ");
n=r.nextInt();
while(n!=0)
{
m=n%10;
sum=sum+m;
n=n/10;
}
System.out.print("Sum
of digits is "+sum);
}
}
MCQ
1.
What does
the expression double n=10/0; return?
a)
0
b)
Infinity
c)
Invalid
Expression
d)
Exception
2.
What is the
reason of portability & security of java?
a)
Bytecode
b)
Applet
c)
Exception
Handling
d)
Dynamic
3.
Which
package contains the System class?
e)
What is
OOP? Full explanation.
OOP stands for object-oriented programming language, the
main purpose of oop is to deal with real world entity using programming
language.
OOPS
Features:
Class
Object
Inheritance
Polymorphism
Encapsulation
Abstraction
What is
class?
Class ids a collection of objects and it doesn’t take any
space on memory, class is also called as blueprint/logical entity.
Type of
class
Pre-define
User-defined
Object:
Object is an instance of class that executes the class. Once
the object is created, it takes up space like other variable in memory.
What is
inheritance? Full explanation.
When we construct a new class from existing class in such a
way that the new class access all the features & properties of existing
class called inheritance.
Note: - in,
java extends keyword is used to
perform inheritance.
It provides code reusability
Polymorphism
Poly + Morphism
Poly means many
and morphism means form
Polymorphism is the Greek word whose meaning is “same object
having different behaviour”.
What is
encapsulation? full explanation.
Encapsulation is a mechanism through which we can wrapping
the data members and member methods of class in a single unit called
encapsulation.
Note: -
Declare the class variables as a private.
Declare the class methods as a public.
Data
Abstraction
Abstraction is a process of hiding the implementation
details from the user, only the highlighted set of services provided to the
user.
Advantage:
Security
Enhancement
Abstraction:
Abstract class
Interface
Data Hiding
Outside users can’t access our internal data directly or our
internal data should not go out directly, this oops feature is nothing but data
hiding.
After Validation and Authentication-----outside user can
access internal data!
working in progress.........
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