## Variables

**V****ariable **is a piece of memory that can contain a data value.

**Variable** is a value that can change, depending on conditions or on information passed to the programme .

**Variable** is name or a single character used to store a value.

A **value** may be quantity, numbers, character, name,etc .

**x**is

**variable**and

**40**is a number that is a value , if we want to store 40 in

**variable**then we need to declare equal to sign between them

**x=40;**now

**x**storing

**40**, it is a value on which operation will be performed, suppose that if you want to add two number then you can just write them like

**40+50**in simple method then add them which is equal to

**40+50=90;**

*but in java how to perform same operation to add number.*

We can’t write the direct value in

**java**means number. we need a

**variable**that will store the value, and then further operation will be performed, to perform this action we need to store the value in variable.

let

**X**is

**variable**that storing the value

**40**, and the another

**variable**

**Y**that storing the value

**50**.

**x=40;**

**y=50;**

here

**x**and

**y**storing the value

**40**and

**50**, now we need another

**variable**that is used to store the value of sum of these number.

let

**z**is a variable that will store the sum of

**x**and

**y**.

**z = x+y;**

now

**z**storing

**90**, which is sum of

**x**and

**y**;

**java Programme to add the value of two variable**

class

**AddNumber**

{

public static void main(

**S**tring[] args)

{

int x=40;

int y=50;

int z=x+y;

**S**ystem.out.println(“The sum of x and y is: “+z);

}

}

**output :** The sum of x and y is : 90

## How to **declare a variable** in **java**

To declare a **variable** in **java** write data type and then **variable name** .

e.g. **int x ;**

here **int** is **data type** and **x** is **variable** .

Click here to read more about **DATA TYPE**

If a **variable** is **int data type** it mean is a **integer** data type mean it will store the value only number without decimal number .

e.g 30 , -45, 4533, etc .

**Types of data type**

**int , double, boolean, String, char.**

**int** store negative and positive integer values (whole numbers). range of **-32768 to +32767**.It is important to note that integers are represented exactly in computer memory.

**float or double** store the **real numeric value**, that is both **whole numbers** and numbers that require digits after the decimal point.The accuracy and the range of numbers represented is dependent on the computer system.

**float 16.315 -0.67 31.567**

**boolean**

**variables** can only hold the values **true or false.** **char** variables represent a single character — a letter, a digit or a punctuation character.

**char ‘+’ ‘A’ ‘a’ ‘*’ ‘7’**

**string** **sequence of characters.** In **java** programming language, strings are treated as objects. The **java** platform provides the String class to create and manipulate strings.

**e.g String x=’name’; x is string variable storing name as a value.**

class

**AddNumber**

{

public static void main(

**S**tring[] args)

{

double x=40.44;

double y=50.44;

double z=x+y;

**S**ystem.out.println(“The sum of x and y is: “+z);

}

}

**output :** The sum of x and y is : 90.88

**java Programme to print the value of a String variable**

class

**PrintString**

{

public static void main(

**S**tring[] args)

{

**S**tring z=”name”;

**S**ystem.out.println(“The sum of x and y is: “+z);

}

}

**output :** The sum of x and y is : name