Java Essentials - For loop in java

in this video we are going to discuss

another looping construct in Java that

is a for loop in Java we know that this

for loop can be applied for those cases

for those et additions where for number

of times the iteration is going to take

place is pre known to us so for loop is

mainly used whether the number of

iterations are pre known to us so when

this number of iterations are pre known

to us then only we can go for the for

loop execution the basic syntax is like

this so far then we are having this

initialization code boolean expression

which can return either true or false

so they will be separated by semicolon

then semicolon then a bit of the loop

control variable and then within curly

braces will be writing the statements

which are under the for loop and

supposed to get executed when the

condition is true so in the

initialization phase it initializes the

loop variable so let us suppose the I is

the loop variable so here I can write I

is equal to 1 or I is equal to 10 so

that is the loop initialization phase in

the boolean expression section it checks

whether the given condition is true or

false

finally it updates the loop control

variable here in this particular section

and these three statements are to be

separated by two semicolons

so each different section for the for

loop like initialization condition

checking and update are separated by a

semicolon so we can use this for loop

for the infinite looping using this

construct here here you can find that

only we have mentioned two semicolons

there is no initialization code there is

no condition and there is no update

score there so that is why we have put

this within this first brackets where

put this semicolon twice and this is

forming an infinite loop

so through this flowchart let us explain

more so control is coming from here this

is our init code or initialization code

then condition is there this butt

the condition when it is true then the

code block will get executed consisting

of single of more multiple statements

then the increment or decrement may take

place so a bit of the loop control

variable will take place but here you

have mentioned increment so also I'm

mentioning increment here then control

is coming back to the condition and when

this condition is true again this

looping will take less executing this

code block once again but if the

condition is false it will come out and

the program will get terminated after

executing the next unexecuted

instructions so let us go for one

practical demonstration for the better

understanding on this for loop in our

java program in this demonstration you

are discussing about the for loop in

Java so int sum is equal to 0 so the sum

has got initialized with a value 0 of

the type integer

and then for int a is equal to 0

semicolon I less than 10 semicolon a

plus plus that means here we were

defining one variable and easily

initializing it with 0 so there is a

loop control variable here the a is

known as the loop control variable so at

first the initialization then semicolon

then you will be having one condition

depending upon the condition it will be

decided whether the loop will get

executed further or it will get

terminated and then semicolon and then

we'll be having increment or decrement

factor or this a of this particular loop

control variable so at first

initialization then semicolon then

condition then semicolon then increment

or decrement of the loop control

variable value so this is a basic syntax

the basic grammar of this 4 so now when

this condition will be true when this

condition will be true then this block

will get executed what we are doing here

actually we are printing one line and

then we are going for sum is equal to

sum plus a and outside of the loop sum

has got initialized with the value 0 so

it can have maximum value as it is

getting increased by one starting from 0

so a can have maximum value that is 9

but at 9 less than 10 the condition will

be true so this sum can't add with the

values ranging from 0 to

9 because a can range from zero tonight

because after nine when the value of a

will get incremented by one when the

value of a gay will get incremented by

one so it will become 10 so 10 less than

10 the condition will become false it

will come out from the loop for loop and

this line will get printed so let us go

for the execution for the better

crediting you can find that the value of

a is ranging from 0 to 9 and these

values are getting added with the sum

and at the end after getting out from

the loop we're printing that the value

of sum is 45 that means when the value

of a will be equal to 10 then it is

coming out from the loop so that's why

if we print the value of a outside here

if you print the value of a outside of

this loop I am expecting that it will

print the value a as 10 here so let us

go for the execution one error is there

so I am just going for this sprinting

is the loop control variable so that's

why it is not having the scope outside

so it is better to go forward here int a

okay so I'm defining this a if we write

this int a here this that means this

scope will be confined within this for

loop only so not accessible from the

outside but if I define this vegetable a

outside of this loop then obviously it

is accessible after the for loop also so

now let me go for the execution you can

find that a is equal to 10 you are

finding the value of a is becoming 10 so

10 less than 10 the condition is

becoming false so that's why it is

coming out from the loop now see instead

of having this we are not erasing the

semicolon instead of having this also

you can write directly here okay so now

let me go for the execution you can find

we are going to have the same output

instead of right writing this a plus

plus instead of writing this a plus plus

here I can also put this a plus plus

here I can also put this a plus plus

here you can find that we're having the

same output whatever you are getting but

don't omit the semicolon so semicolons

should be there but you can have this

initialization statement and this

increment or decrement statement in

other part if I write a plus plus here

so let me go for another experiment if I

write a plus plus so you see for each

and every iteration a is getting

incremented by one here and then one

here so a is getting incremented by two

for each and every tradition so if I go

for the execution you can find that the

value of a will get incremented by two

always so after coming out from eight it

is becoming 10 so when it is becoming 10

it is coming out from the loop and now

we are getting this 10 as a final value

for a after coming out from the loop so

0 plus 2 is 2 plus 4 is 6 plus 6 is 12

plus 8 so I'm getting here 20 as a sum

so I think now the conception is getting

clear to you that how to use a for loop

in our Java code and whenever we require

some iteration with equal some looping

if we get some repetitive work you can

use for we can use do-while or you can

use while do

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