• A.razaq

T4- variables in java

variables in java are locations in memory that store a specific value , in another meaning they are a container that hold and store data during the execution of the java program .

types of variables :

  • String : stores text values .

  • integers : holds and stores integers (whole numbers), without decimals, such as ( 456 ) or ( -456 ).

  • Float and Double : stores real numbers ( contain decimal points), such as in( 3.4 ) , (0.0) and (–11.19).

  • Boolean : stores values with two states: true or false.

  • char : holds single characters, such as 'a' or 'A' , it can be uppercase letter or lowercase.


how can we use variables in java ?

any variable in java first must be declared with a type and a name

before we even use it, for example

lets say we want to declare an integer variable

first we declare the type and in java integers are represented by " int "


then we give it a name , lets use "x" as our variable name

int x 

then if we have a known value we want to assign to the variable x

we place an equal sigh " = " then put the value after.

for example, if we want to give the variable x a value of 10

it will be like this.

int x = 10; 

and we must always end with a semicolon ;

also we must put the correct value type

meaning , we cant declare an integer variable and then assign a decimal value to it

for example

int x = 10.5; <<<< is incorrect 

because integers are without decimal so we use float or double in this case

double x = 10.5;

string variables :

same as any variable , we declare the type String and first letter of String is capital letter

then we give it a name then a value after the equal sign between a double " " quotation marks then end with a semicolon ;

String name = " john";

we can also declare a variable without a value and give it a value later on

int x ;

in this case we have created an integer variable called x without a value

we can assign a value to it later on like this

int x ; 

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