Java Programming Tutorial - 48 - final Video Lecture | Java Programming Fundamentals: For Beginners - Back-End Programming

what's up YouTube welcome to your 48th
draft tutorial and in this tutorial
we're going to be going over instance
variables with the final like when you
have like public final or private final
int that's where we're going to be going
over so unlike static I'm going to be
showing you guys what final means so
let's go ahead and in your tuna class
right here and this is the one that's
not your main apples isn't has my main
method so go into another one I name my
tuna
you can name where yours whatever you
want as long as it's a fish that's key
it has to be fish or this program won't
work I'm just kidding but you know just
a little joke and let's go ahead and the
first thing we're going to want to do is
make a variable that's going to be
private as well but you got to spell it
right that's key private there we go I
know I get eventually into some and what
this is going to do is hold the sum of
our numbers that we're about to add up
now let's like begin the tutorial what
we want to do now is make variable with
the type final so private final and it's
going to be an integer variable and I
hit button there embarrassing and let's
just name it number or something and go
ahead and put it in caps because it's
going to be constant so we know that the
constants aren't caps cook cook there
you go
cut cut that's how you can remember it
so now the key or what final is is
whenever you write final in front of a
variable or constant it means that you
can't modify this no matter what so we
just declared it whenever we set it
equal to something whatever we set it
equal to we can only set it equal to it
once so if we put number equals two then
that number is going to be two for the
rest of your life you can't change in
Tamara watt but another thing is we
declared it right there
but we didn't initialize it which means
we didn't set it equal to anything so
we're going to have to do that in our
constructor so again you can either do
right here or you're in your constructor
so let's go ahead
and make a constructor put public tuna
and just put int X it's going to be a
temporary variable and then put number
equal to X so whatever we pass in for
our argument that's what number is going
to be equal to and again don't mess it
up because you can't change this you
can't later in your program right all
right we're set it equal to two here but
we're going to set equal to fifteen
later on or eighteen or 32 you can't you
can only set it equal to something here
and it stays like that forever now let's
go ahead and build another method so
let's go ahead and write public void
make it called add because what's it
going to do it's going to take that sum
that we have up here and it's going to
be zero default and let's just add the
number to it so again the sum variable
is going to change but this number is
always going to be like 10 or whatever
we say this and now let's just build one
more method so we can actually see
what's going on public string to string
so again you learn a to string method
did last time whenever you need your
object in a string format it returns it
so let's go ahead and return string
format and idly started filling out for
us the format just can be put some like
sum is equal to percent D and then put
like a newline for good looks and then
for your arguments just put some so this
is going to change because it's the
number that stays the same and not the
sum and how do we know that because
number variable is final and sum is just
private sum can change so now that we
got that look it over and make sure it's
the exact same as mine we can go to our
our main class which is apples in this
case so go ahead and let's create an
object so tuna tuna object equals new
tuna and let's go ahead and put
something like 10 so now well this is
going to do since we passed in 10 to our
constructor it's going to take 10 for X
put 10 for X right here and set number
equal to 10
so now for this object number equals 10
no matter what we can't change that so
anytime we use number like at number 2
some we add 10 to some simple enough so
now let's go ahead in well let's go
ahead and make a for loop using this
object so let's just put 4 and let's
make a simple loop put like int I equals
0 if I is less than 5 in I plus plus so
it loops 5 times 1 through 3 loops 5
times it really doesn't matter what you
have inside your for loop this is
important just how to make make
something real quick now we can go sit
ahead and say what do we want to do 5
times well let's go ahead and add on
let's call this a method 5 times so the
first time it's going to be 10 when it
adds it the second not time it's going
to add another 10 to it so it's going to
be 20 then it's going to be 30 40 50
simple enough so let's go ahead and add
tuna object and how you use it is add
right there so now we did our method um
five times but we can't really see
anything because this method right here
it doesn't return anything so we need to
return it right here so let's go go
ahead and put system out let's go ahead
and let's do a print format and let's
just go ahead for the format we'll put
something like let's keep a simple % s
and for the arguments let's just go
ahead and put tuna object so let me go
ahead and run through this and show you
guys the results sum equals 10 some
equals 20 30 40 50 so now let me talk
you guys one last time why this happened
make sure hopefully I'm in my screen
recorder and good enough so what we did
is we made two variables well let's just
go ahead and do this way we made an
object called new tuna or tuna object
was the name of our object and we passed
the parameters 10 for the constructor
so it took that 10 and set number equal
to 10 all right simple enough what's
next
well we loop through this five times so
what did we do five times we did this
add method five times so first four add
it took that number ten and added some
so now sum was equal to ten then it just
spit out 10 and then the next time on
round number two it took that 10 and
added it to 10 then we got 20 so now it
spit it out 20 then it took 10 and added
to 20 which was 30 then added it to 30
which is 40 then added it to 40 which is
50 so now that that's all done so that
is pretty much your really detailed
tutorial on a really simple explanation
that whenever you make a final variable
you cannot change it so for example if
we say down here
um tuna object number equals 15 look at
this right here we get X right here the
filled tuna number is not visible that
means that it can't change pretty much
so that's pretty much all in all I could
have skipped this whole tutorial and set
our when you're right final instead of a
variable it means you can't change it
but I didn't I decided to give you guys
the whole spiel instead so thank you
guys for watching and hey if anyone
wants to do fantasy football with me um
leave a comment and let me know because
I wanted to fantasy football with
someone so thank you guys for watching
and don't forget to subscribe and I'll
see you next time