Java Programming Tutorial - 17 - Constructors Video Lecture | Java Programming Fundamentals: For Beginners - Back-End Programming

so guys bulky welcome to your 17th java
tutorial and this story I'm going to
show you guys about something called a
constructor now what a constructor does
is it allows you to initialize variables
as soon as you create an object so for
example whenever you created this
variable right here as soon as you
created your object let's go ahead and
do that right now
tuna let's make them call tuna object
like before equals new tuna and of
course we had empty brackets as soon as
we did that and try to use our object
such as tuna object saying and what we
do it if we ran this it said your first
girlfriend is null and this would be
because whenever we try to use girl name
it didn't have a value yet well what a
constructor allows you to do is give
this variable of value as soon as you
create your object so let me show you
guys how to make a constructor and then
I'll talk you guys through it one more
time exactly what does now how you make
a constructor is pretty much exactly how
you make a method the only difference is
the methods name has to be the exact
same thing as the class name so let's go
ahead and write public tuna and as you
can see since we're working in the class
called tuna a constructor method has to
also be called tuna so let's go ahead
and what I want this to do is assign a
value to this string variable girl name
so let's go ahead and write string name
of course and I'm going to have this do
the exact same thing is this set named
it so girl name equals name the only
difference is instead of having to call
the setname method we can just do it all
as soon as we create our object so let's
go ahead and now we have a constructor
object that we're going to well let me
just show you guys what it does so
instead of before whenever we use empty
parameters right here we can use those
parameters
to pass an argument such as Kelsey now
let's go ahead and run this and it says
your first girlfriend was Kelsey so that
is a really a simple way of how you can
use a constructor let me talk you guys
through this one more time and then I'll
show you guys another neat little trick
and if you want to initialize a variable
before or excuse me as soon as you
create your object such as this all you
have to do is create a method and name
it the exact same thing is your class
and all you have to do is put whatever
you want to initialize in here and then
whenever you create your object instead
of leave them those parameter parameters
empty
just put your argument in there and that
will go to your constructor and
initialize all those variables for you
so if you're saying RA Y is building a
constructor even remotely useful why
can't I just leave those empty like
before and use this little method right
here later on well say you had more than
one object so say you had another object
called tuna object 2 and another thing I
want to point out I don't know if I told
you guys this before
but every time you have an object it has
its own set of variables so for example
say you have something in this one
called Nicole I wasn't named my second
girlfriend appropriately named to an
object - and say you have a tuna object
to this variable that is what was it
called girl name this is an entirely
different variable than this these two
objects they can't see each other's
variables so that's the kind of beauty
of creating object that gets his own set
of variables so now this object can have
output saying and now you can also have
a saying for tuna object to not 21
saying and let's see what this one does
right here it says your first girlfriend
was Kelsey your first girlfriend was
Nicole
so let me got give you guys will run
down one last time the first thing you
did is create a constructor and again
you did that by naming a method the
exact same thing is a class what this
constructor allowed you to do is allowed
you as soon as you created an object and
we created two of them right here
it took that value and passed it in a
girl name and from there you can you
just use a girl name anytime you want to
use that object so it use girl name
which is Kelsey and tuna object and girl
name which was Nicole and tuna object to
and pass the end of the method saying
for both so again that's not as
important as how to create an object or
excuse me a constructor and again one
last time what a constructor does is it
allows you to initial eyes variables as
soon as an object is created so that's
your real quick tutorial on how to use a
constructor and what it does and will be
coming across that later on and it'll be
get easier and easier as I'll show you
guys how to use it in a more useful
application but for now I just want to
show you guys the basics so thank you
guys for watching make sure to subscribe
to my channel make sure to check out all
my contests and I guess I'll see you
next tutorial